Question

Find out which operation must be done on both sides of these equations in order to solve them.
(1) x + 9 = 11 (2) x $-$ 4 = 9 (3) 8x = 24 (4) $\frac{x}{6}=3$

Answer 1

(1) Subtract 9 from both sides

x + 9 = 11

⇒ x + 9 − 9 = 11 − 9 (Subtract 9 from both sides)

⇒ x + 0 = 2

⇒ x = 2

(2) Add 4 to both sides

x − 4 = 9

⇒ x − 4 + 4 = 9 + 4 (Add 4 to both sides)

⇒ x + 0 = 13

⇒ x = 13

(3) Divide both sides by 8

8x = 24

⇒ $\frac{8x}{8}=\frac{24}{8}$ (Divide both sides by 8)

⇒ x = 3

(4) Multiply both sides by 6

$\frac{x}{6}=3$

⇒ $\frac{x}{6}\times 6=3\times 6$ (Multiply both sides by 6)

⇒ x = 18