Solving an inequality is just like solving equations except for one important rule:
IF YOU MULTIPLY OR DIVIDE BY A NEGATIVE, CHANGE THE DIRECTION OF THE INEQUALITY!
So, proceed as if you are solving for a in this problem.
Rearrange terms to get 3a - 6a + 3 > 15
Combine like terms to get -3a + 3 > 15
Subtract 3 from both sides to get -3a > 12
DIVIDE BY -3 on both sides to get a < 4.
Do the algebra and apply the special rule only when you multiply or divide by a negative.