Question

Find out which operation must be done on both sides of these equation in order to solve them.

x – 4 = 9

Answer 1

Add 4 to both sides

x − 4 = 9 

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

⇒ x + 0 = 13

⇒ x = 13