Question

21 = 4x - 9 - x
what is x?

Answer 1

x = 10

Explanation:

Given

21 = 4x - 9 - x, that is

21 = 3x - 9 ( add 9 to both sides )

30 = 3x ( divide both sides by 3 )

10 = x

Answer 2

x = 10

Explanation:

21 = 4x - 9 - x

21 = 3x - 9

30 = 3x

10 = x