Question
Class 7MathematicsSimple Equations

Solve the following equations and check the answers.

(a) 5z+1/3 = 7

(b) 5x/3 + 3 = x + 7

Verified Answer

(a) (5z + 1)/3 = 7

       ⇒ (5z + 1)/3 × 3 = 7 × 3 (Multiplying both sides by 3)

       ⇒ 5z + 1 = 21

       ⇒ 5z = 21 − 1 (Transposing 1 to RHS)

       ⇒ 5z = 20

       ⇒ z = 20/5 (Dividing both sides by 5)

       ⇒ z = 4

       Check: Put z = 4 in LHS

      (5 × 4 + 1)/3 = 20 + 1/3 = 21/3 = 7 RHS as required.

(b) (5x/3) + 3 = x + 7 − 3

       ⇒ (5x/3) − x = 4 (Transposing 3 to RHS and x to LHS)

       ⇒ (5x − 3x)/3 = 4

       ⇒ 2x/3 = 4 (Multiplying both sides by 3)   

       ⇒ 2x = 12

       ⇒ x = 12/2 (Dividing both sides by 2)

       ⇒ x = 6

       Check: Put x = 6 in LHS

       (5 × 6)/3 + 3 = 10 + 3 = 13

       Put x = 6 in RHS

       x + 7 = 13

       LHS = RHS

      Hence verified.