15-87=x

Solution for 15-87=x equation:

Simplifying
15 + -87 = x

Combine like terms: 15 + -87 = -72
-72 = x

Solving
-72 = x

Solving for variable 'x'.

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

Add '-1x' to each side of the equation.
-72 + -1x = x + -1x

Combine like terms: x + -1x = 0
-72 + -1x = 0

Add '72' to each side of the equation.
-72 + 72 + -1x = 0 + 72

Combine like terms: -72 + 72 = 0
0 + -1x = 0 + 72
-1x = 0 + 72

Combine like terms: 0 + 72 = 72
-1x = 72

Divide each side by '-1'.
x = -72

Simplifying
x = -72