Divide both sides by -3 to isolate a (note: dividing by both sides by a negative number flips the inequality sign)
Divide
--------------------------------------------------------------
Answer:
So our answer is
Now let's graph the solution
Start with the given inequality:
Set up a number line:
note: just replace the x with the variable you are working with
Now plot the point a=7 on the number line
Now pick any test point you want, I'm going to choose a=0, and test the inequality
Plug in
Since this inequality is not true, we simply shade the entire portion that does not contain the point a=0 using the point a=7 as the boundary. This means we shade everything to the right of the point a=7 like this:
Graph of with the shaded region in blue
note: at the point a=7, there is an open circle. This means the point a=7 is excluded from the solution set.