3(1[2u-9]1)=15

Solution for 3(1[2u-9]1)=15 equation:

Simplifying
3(1[2u + -9] * 1) = 15

Reorder the terms:
3(1[-9 + 2u] * 1) = 15

Reorder the terms for easier multiplication:
3(1 * 1[-9 + 2u]) = 15

Multiply 1 * 1
3(1[-9 + 2u]) = 15
3([-9 * 1 + 2u * 1]) = 15
3([-9 + 2u]) = 15
(-9 * 3 + 2u * 3) = 15
(-27 + 6u) = 15

Solving
-27 + 6u = 15

Solving for variable 'u'.

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

Add '27' to each side of the equation.
-27 + 27 + 6u = 15 + 27

Combine like terms: -27 + 27 = 0
0 + 6u = 15 + 27
6u = 15 + 27

Combine like terms: 15 + 27 = 42
6u = 42

Divide each side by '6'.
u = 7

Simplifying
u = 7