90=a

Solution for 90=a equation:

Simplifying
90 = a

Solving
90 = a

Solving for variable 'a'.

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

Add '-1a' to each side of the equation.
90 + -1a = a + -1a

Combine like terms: a + -1a = 0
90 + -1a = 0

Add '-90' to each side of the equation.
90 + -90 + -1a = 0 + -90

Combine like terms: 90 + -90 = 0
0 + -1a = 0 + -90
-1a = 0 + -90

Combine like terms: 0 + -90 = -90
-1a = -90

Divide each side by '-1'.
a = 90

Simplifying
a = 90