43=a-21

Solution for 43=a-21 equation:

Simplifying
43 = a + -21

Reorder the terms:
43 = -21 + a

Solving
43 = -21 + 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.
43 + -1a = -21 + a + -1a

Combine like terms: a + -1a = 0
43 + -1a = -21 + 0
43 + -1a = -21

Add '-43' to each side of the equation.
43 + -43 + -1a = -21 + -43

Combine like terms: 43 + -43 = 0
0 + -1a = -21 + -43
-1a = -21 + -43

Combine like terms: -21 + -43 = -64
-1a = -64

Divide each side by '-1'.
a = 64

Simplifying
a = 64