(t-2)+t+(t+2)=21

Solution for (t-2)+t+(t+2)=21 equation:

Simplifying
(t + -2) + t + (t + 2) = 21

Reorder the terms:
(-2 + t) + t + (t + 2) = 21

Remove parenthesis around (-2 + t)
-2 + t + t + (t + 2) = 21

Reorder the terms:
-2 + t + t + (2 + t) = 21

Remove parenthesis around (2 + t)
-2 + t + t + 2 + t = 21

Reorder the terms:
-2 + 2 + t + t + t = 21

Combine like terms: -2 + 2 = 0
0 + t + t + t = 21
t + t + t = 21

Combine like terms: t + t = 2t
2t + t = 21

Combine like terms: 2t + t = 3t
3t = 21

Solving
3t = 21

Solving for variable 't'.

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

Divide each side by '3'.
t = 7

Simplifying
t = 7