2a-21=a

Solution for 2a-21=a equation:

Simplifying
2a + -21 = a

Reorder the terms:
-21 + 2a = a

Solving
-21 + 2a = 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.
-21 + 2a + -1a = a + -1a

Combine like terms: 2a + -1a = 1a
-21 + 1a = a + -1a

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

Add '21' to each side of the equation.
-21 + 21 + 1a = 0 + 21

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

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

Divide each side by '1'.
a = 21

Simplifying
a = 21