**Simple Equations NCERT Solution for Class 7 Maths Chapter 4 Exercise 4.3**

**Simple Equations Class 7 Ex. 4.3;**

**Simple Equations Class 7 Ex. 4.1**

**Simple Equations Class 7 Ex. 4.2**

**Exercise 4.3**

**Simple Equations Chapter 4 NCERT Math Ex.-4.3.**

**Question 1:- Set-up equations and solve them to find the unknown numbers in the following cases:**

**(a) Add 4 to eight times a number; you get 60.**

**(b) One-fifth of a number minus 4 gives 3.**

**(c) If I take three-fourths of a number and add 3 to it, I get 21.**

**(d) When I subtracted 11 from twice a number, the result was 15.**

**(e) Munna subtracts thrice the number of notebooks he has from 50, he finds the result to be 8.**

**(f) Ibenhal thinks of a number. If she adds 19 to it and divides the sum by 5, she will get 8.**

**(g) Anwar thinks of a number. If he takes away 7 from 5÷2 of the numbers, the result is 23.**

**Solution 1:-**

(a) Let the required number be x.

So, the required equation will be

8x + 4 = 60

8x = 60 – 4

⇒ 8x = 56

⇒ (8x)/8=(56)/8 (Dividing both sides by 8)

⇒ x = 7

Thus, x = 7; required unknown number.

(b) Let the required number be x.

So, the required equation will be

(1/5)x – 4 = 3

⇒ x/5 =4 + 3 (Transposing 4 to RHS)

⇒ x/5= 7

⇒ (x/5)X5 =7X5 (Multiplying both sides by 5)

⇒ x = 35; required unknown number,

(c) Let the required number be x.

(3/4)x + 3 = 21 is the required equation.

Solving the equation, we have

(3/4)x = 21-3

(3/4)x = 18

x = 18(4/3)

x= 6×4

x = 24. (required unknown number).

(d) Let, the required unknown number be x.

2x -11 = 15 ( the required equations ).

Solving the equation, we have

2x – 11= 15

⇒ 2x = 15 + 11 (Transposing 11 to RHS)

⇒ 2x = 26

⇒ (2x)/2=26/2 (Dividing both sides by 2)

⇒ x = 13 is the required unknown number,

(e) Let the required number be x.

50 – 3x = 8 ( required equations ).

Solving the equation, we have

50 – 3x = 8

-(3)x = 8 – 50 (Transposing 50 to RHS)

⇒ -(3)x = -(42)

⇒ −(3x)/−3=−(42)/−(3) (Dividing both sides by -3)

⇒ x = 14 is the required unknown number.

(f) Let the required number be x.

(x+19)/5 = 8 is the required equation.

Solving the equation, we have

(x+19)/5 = 8

⇒ (x+19)/5 × 5 = 8 × 5(Multiplying both sides by 5)

⇒ x + 19 = 40

x = 40 – 19 (Transposing 19 to R.H.S)

So, x = 21 ( the required unknown number).

(g) Let the required number be x.

(5/2)x – 7 = 23 is the required equation.

Solving the equation, we have

(5/2)x = 23+7

(5/2)x =30

x= 30x(2/5)

x= 6×2

x = 12. ( the required unknown number ).

**Question 2 :- Solve the following:**

**(a) The teacher tells the class that the highest marks obtained by a student in her class is twice the lowest marks plus 7. The highest score is 87. What is the lowest score?**

**(b) In an isosceles triangle, the base angle are equal. The vertex angle is 40°. What are the base angles of the triangle? (Remember, the sum of three angles of a triangle is 180°?)**

**(c) Sachin scored twice as many runs as Rahul. Together, their runs fell two short of a double century. How many runs did each one score?**

**Solution 2:-**

(a) Let the lowest score be x.

2x + 7 = 87 is the required equation. Solving the equation, we have

2x = 87 – 7 (Transposing 7 to R.H.S)

⇒ 2x = 80

⇒ (2x)/2=80/2 (Dividing both sides by 2)

x = 40. (the required lowest marks).

(b) Let each base angle be x degrees.

Sum of all angles of the triangle = 180 degree

x + x + 40 = 180°

⇒ 2x + 40° = 180°

Solving the equation, we have

2x + 40° = 180°

2x = 180° – 40° (Transposing 40° to RHS)

2x = 140°

⇒ (2x)/2=140/2 (Dividing both sides by 2)

⇒ x = 70°

Thus the required each base angle = 70°

(c) Let the runs scored by Rahul = x

Runs scored by Sachin = 2x

x + 2x = 200 – 2

Solving the equation, we have

3x = 198

⇒ (3x)/3=198/3 (Dividing both sides by 3)

⇒ x = 66

Thus, the runs scored by Rahul is 66 and the runs scored by Sachin = 2 × 66 = 132.

**Question 3 :- Solve the following:**

**(i) Irfan says that he has 7 marbles more than five times the marbles Parmit has. Irfan has 37 marbles. How many marbles does Parmit have?**

**(ii) Laxmi’s father is 49 years old. He is 4 years older than three times Laxmi’s age. What is Laxmi’s age?**

**(iii) People of Sundargram planted trees in the village garden. Some of the trees were fruit trees. The number of non-fruit trees were two more than three times the number of fruit trees. What was the number of fruit trees planted if the number of non-fruit trees planted was 77?**

**Solution 3:- **

(i) Let the number of marbles with Parmit be x

Number of marbles that Irfan has = 5x + 7

5x + 7 = 37

⇒ 5x = 37 – 7 (Transposing 7 to RHS)

⇒ 5x = 30

⇒ (5x)/5=30/5 (Dividing both sides by 5)

⇒ x = 6

Thus, the required number of marbles = 6.

(ii) Let Laxmi’s age be x years.

Laxmi’s Father’s age = 3x + 4

3x + 4 = 49

⇒ 3x = 49 – 4 (Transposing to RHS)

⇒ 3x = 45

⇒ (3x)/3=45/3 (Dividing both sides by 3)

⇒ x = 15

Thus, the age of Laxmi = 15 years

(iii) Let the number of planted fruit tree be x.

Number of non-fruit trees = 3x + 2

3x + 2 = 77

⇒ 3x = 77 – 2 (Transposing 2 to RHS)

⇒ 3x = 75

⇒ (3x)/3=75/3 (Dividing both sides by 3)

⇒ x = 25

Thus, the required number of fruit tree planted = 25

**Question 4 :- Solve the following riddle:**

**I am a number,**

**Tell my identity!**

**Take me seven times over**

**And add a fifty!**

**To reach a triple century**

**You still need forty!**

**Solution 4:-**

Suppose my identity number is x.

7x + 50 + 40 = 300

7x + 90 = 300

⇒ 7x = 300 – 90 (Transforming 90 to RHS)

⇒ 7x = 210

⇒ (7x)/7 = 210/7 (Dividing both sides by 7)

⇒ x = 30

Thus, my identity is 30.

**Simple Equations Chapter 4 NCERT Math Ex.-4.3.**