Answer:
Explanation:
Simplifying
3(2x + -1) = 21
Reorder the terms:
3(-1 + 2x) = 21
(-1 * 3 + 2x * 3) = 21
(-3 + 6x) = 21
Solving
-3 + 6x = 21
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '3' to each side of the equation.
-3 + 3 + 6x = 21 + 3
Combine like terms: -3 + 3 = 0
0 + 6x = 21 + 3
6x = 21 + 3
Combine like terms: 21 + 3 = 24
6x = 24
Divide each side by '6'.
x = 4
Simplifying
x = 4