# NCERT Solution class 7 Mathematics EXERCISE- 4.2

# CHAPTER – 4

# EXERCISE – 4.2

**Q1. Give first the step you will use to separate the variables and then solve the equation:**

**(i) x – 1 = 0**

**SOLUTION:-**

x-1 +1 = 0 +1

= x = 1

**(b) x + 1 = 0**

**SOLUTION:-**

= x + 1 – 1 = 0 – 1

= x = -1

**(c) x – 1 = 5**

**SOLUTION:-**

= x – 1 + 1 = 5 + 1

= x = 6

**(d) x + 6 = 2**

**SOLUTION:-**

= x – 1 + 1 = 5 + 1

= x = 6

**(d) x + 6 = 2**

**SOLUTION:-**

= X + 6

= X = -4

**(E) y – 4 = -7**

**SOLUTION:-**

= y – 4 +4 = -7 + 4

= = y = -3

**(f) y – 4 = 4**

**SOLUTION:-**

= y – 4 + 4 = 4 + 4

= y = 8

**(g) y + 4**

**SOLUTION:-**

= Y +4 – 4 = 4 – 4

= Y = 0

**(H) y + 4 = -4**

**SOLUTION:-**

= y + 4 – 4 = -4 – 4

= Y = -8

**Q2. Give first the step you will use to separate the variable and then solve the equation:**

**(a) 3 L = 42**

**SOLUTION:-**

= L = 42/3

= L = 14

**(B) B/2 = 6**

**SOLUTION:-**

B = 6 X 2

B = 12

**(C) P/7 = 4**

**SOLUTION:-**

P = 4 X 7

`P = 28

**(d) 4x = 25**

**SOLUTION:-**

= x = 25/4

= x = 5.1

**(e) 8y = 36**

**SOLUTION:-**

= y = 36/8

= y = 4.5

**(f) z/3 = 5/4**

**Solution:-**

= z = 15/4

= z = 3.75

**(g) a/5 = 7/15**

**SOLUTION:-**

= a = 35/15

= a = 7/3

= a = 2.9

**(h) 20t = -10**

**SOLUTION:-**

= t = = -1/2

**Q3.Give the steps you will use to separate the variable and then solve the equation:**

**(a) 3n – 2 = 46**

**SOLUTION:-**

3n = 46 +2

3n = 48

n = 48/3

n = 16

**(b) 5m + 7 =17**

**SOLUTION:-**

5m = 17 – 7

5m = 10

m = 10/2

m = 5

**(c) 20p/3 = 40**

**SOLUTION:-**

= 20p = 120

= p = 120/20

= p = 6

**(d) 3p/10 = 6**

**SOLUTION:-**

= 3p = 6 x 10

= 3p = 60

= p = 60/3

= p = 20

**Q4. Solve the following equations:**

**(a) 10p=100**

**SOLUTION:-**

= 10p = 100

= p = 100/10

= p = 10

**(b) 10p + 10 = 100**

**SOLUTION:-**

= 10p = 100-10

= 10 p = 90

= p = 9

**(c) p/4 = 5**

**SOLUTION:- **

= p = 20

**(d) –p/3 = 5**

**SOLUTION:- **

= -P = 15

**(E) 3p/4 = 6**

**SOLUTION:-**

= 3p = 24

= p = 24/3

= p = 8

**(f) 3s = -9**

**SOLUTION:-**

= s = -9/3

= s = -3

**(g) 3s + 12 = 0**

**SOLUTION:-**

= 3s = -12

= s = -4

**(h) 3s = 0**

**SOLUTION:-**

= s = 0

**(i) 2q = 6**

**SOLUTION:-**

q = 6/2

q = 3

**(j) 2q – 6 = 0**

**SOLUTION:-**

= 2q = 6

= q = 6/2

= q = 3

**(k) 2q + 6 = 0**

**SOLUTION:-**

= 2q = -6

= q = -6/2

= q = -3

**(i) 2q + 6 = 12**

**SOLUTION:-**

= 2q = 12-6

= 2q = 6

= q = 6/2

= q = 3

** **