-6(a+7)=-90

Solution for -6(a+7)=-90 equation:

Simplifying
-6(a + 7) = -90

Reorder the terms:
-6(7 + a) = -90
(7 * -6 + a * -6) = -90
(-42 + -6a) = -90

Solving
-42 + -6a = -90

Solving for variable 'a'.

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

Add '42' to each side of the equation.
-42 + 42 + -6a = -90 + 42

Combine like terms: -42 + 42 = 0
0 + -6a = -90 + 42
-6a = -90 + 42

Combine like terms: -90 + 42 = -48
-6a = -48

Divide each side by '-6'.
a = 8

Simplifying
a = 8