NCERT Solutions
Class 7 Maths
Simple Equations

Ex.4.2 Q.4
Solve the following equation:
(a) 10p = 100
(b) 10p + 10 = 100
(c) = 5
(d) = 5
(e) = 6
(f) 3s = -9
(g) 3s + 12 = 0
(h) 3s = 0
(i) 2q = 6
(j) 2q – 6 = 0
(k) 2q + 6 = 0
(l) 2q + 6 = 12
(a) 10p = 100
=> [Dividing both sides by 10]
=> p = 10
(b) 10p + 10 = 100
=> 10p + 10 – 10 = 100 – 10 [Subtracting 10 on both sides]
=> 10p = 90
=> [Dividing both sides by 10]
=> p = 9
(c) = 5
=> * 4 = 5 * 4 [Multiplying both sides by 4]
=> p = 20
(d) = 5
=> * (-3) = 5 * (-3) [Multiplying both sides by (-3)]
=> p = -15
(e) = 6
=> * 4 = 6 * 4 [Multiplying both sides by 4]
=> 3p = 24
=> [Dividing both sides by 3]
=> p = 8
(f) 3s = -9
=> [Dividing both sides by 3]
=> s = -3
(g) 3s + 12 = 0
=> 3s + 12 – 12 = 0 – 12 [Subtracting 12 on both sides]
=> 3s = -12
=> [Dividing both sides by 3]
=> s = -4
(h) 3s = 0
=> [Dividing both sides by 3]
=> s = 0
(i) 2q = 6
=> [Dividing both sides by 2]
=> q = 3
(j) 2q – 6 = 0
=> 2q – 6 + 6 = 0 + 6 [Adding 6 on both sides]
=> 2q = 6
=> [Dividing both sides by 2]
=> q = 3
(k) 2q + 6 = 0
=> 2q + 6 - 6 = 0 – 6 [Subtracting 6 on both sides]
=> 2q = -6
=> [Dividing both sides by 2]
=> q = -3
(l) 2q + 6 = 12
=> 2q + 6 - 6 = 12 – 6 [Subtracting 6 on both sides]
=> 2q = 6
=> [Dividing both sides by 2]
=> q = 3