a+2a+3a-6=7a-b

Solution for a+2a+3a-6=7a-b equation:

Simplifying
a + 2a + 3a + -6 = 7a + -1b

Reorder the terms:
-6 + a + 2a + 3a = 7a + -1b

Combine like terms: a + 2a = 3a
-6 + 3a + 3a = 7a + -1b

Combine like terms: 3a + 3a = 6a
-6 + 6a = 7a + -1b

Solving
-6 + 6a = 7a + -1b

Solving for variable 'a'.

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

Add '-7a' to each side of the equation.
-6 + 6a + -7a = 7a + -7a + -1b

Combine like terms: 6a + -7a = -1a
-6 + -1a = 7a + -7a + -1b

Combine like terms: 7a + -7a = 0
-6 + -1a = 0 + -1b
-6 + -1a = -1b

Add '6' to each side of the equation.
-6 + 6 + -1a = 6 + -1b

Combine like terms: -6 + 6 = 0
0 + -1a = 6 + -1b
-1a = 6 + -1b

Divide each side by '-1'.
a = -6 + b

Simplifying
a = -6 + b