Answer:
If your trying to solve for a, I believe this is the answer: a = 4b / (2 - c)
Explanation:
2a - b = ac + 3b
First you want to group by like terms, so for "b" you are going to add "b" to both sides so that it cancels out on the left side and you now have all of your "b's" on the right.
2a = ac + 4b
next, you want to get the a's on the left side so you are going to subtract "ac"
2a - ac = 4b
Now, you need to factor the "a" out, and since its the greatest common factor among the "2a - ac" you are left with "a(2 - c)"
a(2 - c) = 4b
Finally divide both sides by "(2 - c)"
a = 4b / (2 - c)
and that's your answer