ab+7b-3a-21=0

Solution for ab+7b-3a-21=0 equation:

Simplifying
ab + 7b + -3a + -21 = 0

Reorder the terms:
-21 + -3a + ab + 7b = 0

Solving
-21 + -3a + ab + 7b = 0

Solving for variable 'a'.

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

Add '21' to each side of the equation.
-21 + -3a + ab + 21 + 7b = 0 + 21

Reorder the terms:
-21 + 21 + -3a + ab + 7b = 0 + 21

Combine like terms: -21 + 21 = 0
0 + -3a + ab + 7b = 0 + 21
-3a + ab + 7b = 0 + 21

Combine like terms: 0 + 21 = 21
-3a + ab + 7b = 21

Add '-7b' to each side of the equation.
-3a + ab + 7b + -7b = 21 + -7b

Combine like terms: 7b + -7b = 0
-3a + ab + 0 = 21 + -7b
-3a + ab = 21 + -7b

Reorder the terms:
-21 + -3a + ab + 7b = 21 + -7b + -21 + 7b

Reorder the terms:
-21 + -3a + ab + 7b = 21 + -21 + -7b + 7b

Combine like terms: 21 + -21 = 0
-21 + -3a + ab + 7b = 0 + -7b + 7b
-21 + -3a + ab + 7b = -7b + 7b

Combine like terms: -7b + 7b = 0
-21 + -3a + ab + 7b = 0

The solution to this equation could not be determined.