#### Answer

x=7.2

#### Work Step by Step

Simplifying
5(x + -3) = 21
Reorder the terms:
5(-3 + x) = 21
(-3 * 5 + x * 5) = 21
(-15 + 5x) = 21
Solving
-15 + 5x = 21
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '15' to each side of the equation.
-15 + 15 + 5x = 21 + 15
Combine like terms: -15 + 15 = 0
0 + 5x = 21 + 15
5x = 21 + 15
Combine like terms: 21 + 15 = 36
5x = 36
Divide each side by '5'.
x = 7.2
Simplifying
x = 7.2