7a+21=6a+42

Solution for 7a+21=6a+42 equation:

Simplifying
7a + 21 = 6a + 42

Reorder the terms:
21 + 7a = 6a + 42

Reorder the terms:
21 + 7a = 42 + 6a

Solving
21 + 7a = 42 + 6a

Solving for variable 'a'.

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

Add '-6a' to each side of the equation.
21 + 7a + -6a = 42 + 6a + -6a

Combine like terms: 7a + -6a = 1a
21 + 1a = 42 + 6a + -6a

Combine like terms: 6a + -6a = 0
21 + 1a = 42 + 0
21 + 1a = 42

Add '-21' to each side of the equation.
21 + -21 + 1a = 42 + -21

Combine like terms: 21 + -21 = 0
0 + 1a = 42 + -21
1a = 42 + -21

Combine like terms: 42 + -21 = 21
1a = 21

Divide each side by '1'.
a = 21

Simplifying
a = 21