7u+2(u+3)=-21

Solution for 7u+2(u+3)=-21 equation:

Simplifying
7u + 2(u + 3) = -21

Reorder the terms:
7u + 2(3 + u) = -21
7u + (3 * 2 + u * 2) = -21
7u + (6 + 2u) = -21

Reorder the terms:
6 + 7u + 2u = -21

Combine like terms: 7u + 2u = 9u
6 + 9u = -21

Solving
6 + 9u = -21

Solving for variable 'u'.

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

Add '-6' to each side of the equation.
6 + -6 + 9u = -21 + -6

Combine like terms: 6 + -6 = 0
0 + 9u = -21 + -6
9u = -21 + -6

Combine like terms: -21 + -6 = -27
9u = -27

Divide each side by '9'.
u = -3

Simplifying
u = -3