21=3(t-12)

Solution for 21=3(t-12) equation:

Simplifying
21 = 3(t + -12)

Reorder the terms:
21 = 3(-12 + t)
21 = (-12 * 3 + t * 3)
21 = (-36 + 3t)

Solving
21 = -36 + 3t

Solving for variable 't'.

Move all terms containing t to the left, all other terms to the right.

Add '-3t' to each side of the equation.
21 + -3t = -36 + 3t + -3t

Combine like terms: 3t + -3t = 0
21 + -3t = -36 + 0
21 + -3t = -36

Add '-21' to each side of the equation.
21 + -21 + -3t = -36 + -21

Combine like terms: 21 + -21 = 0
0 + -3t = -36 + -21
-3t = -36 + -21

Combine like terms: -36 + -21 = -57
-3t = -57

Divide each side by '-3'.
t = 19

Simplifying
t = 19