=12a-(-(-2a+b)+3b)+(4a-7b)

Solution for =12a-(-(-2a+b)+3b)+(4a-7b) equation:

Simplifying
0 = 12a + -1(-1(-2a + b) + 3b) + (4a + -7b)
0 = 12a + -1((-2a * -1 + b * -1) + 3b) + (4a + -7b)
0 = 12a + -1((2a + -1b) + 3b) + (4a + -7b)

Combine like terms: -1b + 3b = 2b
0 = 12a + -1(2a + 2b) + (4a + -7b)
0 = 12a + (2a * -1 + 2b * -1) + (4a + -7b)
0 = 12a + (-2a + -2b) + (4a + -7b)

Remove parenthesis around (4a + -7b)
0 = 12a + -2a + -2b + 4a + -7b

Reorder the terms:
0 = 12a + -2a + 4a + -2b + -7b

Combine like terms: 12a + -2a = 10a
0 = 10a + 4a + -2b + -7b

Combine like terms: 10a + 4a = 14a
0 = 14a + -2b + -7b

Combine like terms: -2b + -7b = -9b
0 = 14a + -9b

Solving
0 = 14a + -9b

Solving for variable 'a'.

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

Add '-14a' to each side of the equation.
0 + -14a = 14a + -14a + -9b
Remove the zero:
-14a = 14a + -14a + -9b

Combine like terms: 14a + -14a = 0
-14a = 0 + -9b
-14a = -9b

Divide each side by '-14'.
a = 0.6428571429b

Simplifying
a = 0.6428571429b