-21+16=a

Solution for -21+16=a equation:

Simplifying
-21 + 16 = a

Combine like terms: -21 + 16 = -5
-5 = a

Solving
-5 = 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.
-5 + -1a = a + -1a

Combine like terms: a + -1a = 0
-5 + -1a = 0

Add '5' to each side of the equation.
-5 + 5 + -1a = 0 + 5

Combine like terms: -5 + 5 = 0
0 + -1a = 0 + 5
-1a = 0 + 5

Combine like terms: 0 + 5 = 5
-1a = 5

Divide each side by '-1'.
a = -5

Simplifying
a = -5