-2a-(-3(a+7))-4(-a+b)=0

Solution for -2a-(-3(a+7))-4(-a+b)=0 equation:

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

Reorder the terms:
-2a + -1(-3(7 + a)) + -4(-1a + b) = 0
-2a + -1((7 * -3 + a * -3)) + -4(-1a + b) = 0
-2a + -1((-21 + -3a)) + -4(-1a + b) = 0
-2a + (-21 * -1 + -3a * -1) + -4(-1a + b) = 0
-2a + (21 + 3a) + -4(-1a + b) = 0
-2a + 21 + 3a + (-1a * -4 + b * -4) = 0
-2a + 21 + 3a + (4a + -4b) = 0

Reorder the terms:
21 + -2a + 3a + 4a + -4b = 0

Combine like terms: -2a + 3a = 1a
21 + 1a + 4a + -4b = 0

Combine like terms: 1a + 4a = 5a
21 + 5a + -4b = 0

Solving
21 + 5a + -4b = 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 + 5a + -21 + -4b = 0 + -21

Reorder the terms:
21 + -21 + 5a + -4b = 0 + -21

Combine like terms: 21 + -21 = 0
0 + 5a + -4b = 0 + -21
5a + -4b = 0 + -21

Combine like terms: 0 + -21 = -21
5a + -4b = -21

Add '4b' to each side of the equation.
5a + -4b + 4b = -21 + 4b

Combine like terms: -4b + 4b = 0
5a + 0 = -21 + 4b
5a = -21 + 4b

Divide each side by '5'.
a = -4.2 + 0.8b

Simplifying
a = -4.2 + 0.8b