Question

A young boy is growing at a rate of 3.5 cm per month. He is currently 90 cm tall. At that rate, in how many months will the boy grow to a height of 132 cm?

Answer 1

3.5x+90=132
       -90   -90
3.5x=42
x=12

Answer 2

Heightnow+heightgrown=132
heightgrown=3.5 times months (m)
heightnow=90
90+3.5m=132
minus 90 both sides
3.5m=42
divide both sides by 3.5
m=12

12 months