(a-42)+(a-33)=a+21

Solution for (a-42)+(a-33)=a+21 equation:

Simplifying
(a + -42) + (a + -33) = a + 21

Reorder the terms:
(-42 + a) + (a + -33) = a + 21

Remove parenthesis around (-42 + a)
-42 + a + (a + -33) = a + 21

Reorder the terms:
-42 + a + (-33 + a) = a + 21

Remove parenthesis around (-33 + a)
-42 + a + -33 + a = a + 21

Reorder the terms:
-42 + -33 + a + a = a + 21

Combine like terms: -42 + -33 = -75
-75 + a + a = a + 21

Combine like terms: a + a = 2a
-75 + 2a = a + 21

Reorder the terms:
-75 + 2a = 21 + a

Solving
-75 + 2a = 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.
-75 + 2a + -1a = 21 + a + -1a

Combine like terms: 2a + -1a = 1a
-75 + 1a = 21 + a + -1a

Combine like terms: a + -1a = 0
-75 + 1a = 21 + 0
-75 + 1a = 21

Add '75' to each side of the equation.
-75 + 75 + 1a = 21 + 75

Combine like terms: -75 + 75 = 0
0 + 1a = 21 + 75
1a = 21 + 75

Combine like terms: 21 + 75 = 96
1a = 96

Divide each side by '1'.
a = 96

Simplifying
a = 96