3b+7b+2c-a=4

Solution for 3b+7b+2c-a=4 equation:

Simplifying
3b + 7b + 2c + -1a = 4

Reorder the terms:
-1a + 3b + 7b + 2c = 4

Combine like terms: 3b + 7b = 10b
-1a + 10b + 2c = 4

Solving
-1a + 10b + 2c = 4

Solving for variable 'a'.

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

Add '-10b' to each side of the equation.
-1a + 10b + -10b + 2c = 4 + -10b

Combine like terms: 10b + -10b = 0
-1a + 0 + 2c = 4 + -10b
-1a + 2c = 4 + -10b

Add '-2c' to each side of the equation.
-1a + 2c + -2c = 4 + -10b + -2c

Combine like terms: 2c + -2c = 0
-1a + 0 = 4 + -10b + -2c
-1a = 4 + -10b + -2c

Divide each side by '-1'.
a = -4 + 10b + 2c

Simplifying
a = -4 + 10b + 2c