Question

Find x: −3(4x + 9) = 21

Answer 1

Expanding the bracket,

– 3 × 4 + (– 3) × 9 = 21

∴ – 12x + (– 27) = 21

– 12x – 27 = 21

Transposing – 27 to other side, it becomes + 27

– 12x = 21 + 27 = 48

∴ – 12x = 48

⇒ 12x = – 48

Dividing by 12 on both sides

`(12x)/12 = (-48)/12`

⇒ x = – 4