Solve the simple equation and check the results : 3(k + 4) = 21

1.	Solve the simple equation and check the results : 3(k + 4) = 21
Answer» Given 3(k + 4) = 21 ⇒ 3k + 12 = 21 (Distributive property) ⇒ 3k + 12 – 12 = 21 – 12 (Subtract 12 on both sides) ⇒ 3k = 9 ⇒ 3k/3 = 9/3 (Divide by 3 on both sides) ⇒ k = 3 Check: Substitute k = 3 in 3(k + 4) = 21 LHS = 3(k + 4) = 3(3 + 4) = 3 × 7 = 21= RHS Hence verified.

Answer»

Given 3(k + 4) = 21

⇒ 3k + 12 = 21 (Distributive property)

⇒ 3k + 12 – 12 = 21 – 12 (Subtract 12 on both sides)

⇒ 3k = 9

⇒ 3k/3 = 9/3 (Divide by 3 on both sides)

⇒ k = 3

Check:

Substitute k = 3 in 3(k + 4) = 21

LHS = 3(k + 4)

= 3(3 + 4)

= 3 × 7 = 21= RHS

Hence verified.

Discussion