3a-6+4a+5=90

Solution for 3a-6+4a+5=90 equation:

Simplifying
3a + -6 + 4a + 5 = 90

Reorder the terms:
-6 + 5 + 3a + 4a = 90

Combine like terms: -6 + 5 = -1
-1 + 3a + 4a = 90

Combine like terms: 3a + 4a = 7a
-1 + 7a = 90

Solving
-1 + 7a = 90

Solving for variable 'a'.

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

Add '1' to each side of the equation.
-1 + 1 + 7a = 90 + 1

Combine like terms: -1 + 1 = 0
0 + 7a = 90 + 1
7a = 90 + 1

Combine like terms: 90 + 1 = 91
7a = 91

Divide each side by '7'.
a = 13

Simplifying
a = 13