I conclude the triangle is acute
We are given:

Our goal in solving for any variable, in this case is x, we need to isolate x on one side of the variable. Let's start by subtracting 7x from both sides, which will cancel the +7x on the right side. We are then left with:

Now, we want to move that +10 to the other side so our x is all by itself. Let's subtract 10 from both sides, which will cancel the +10 on the right leaving us with:

Since we cannot have a coefficient when solving for x, we need to divide both sides by -3.

When we divide, our answer is:

First subtract the original high from the new high:
567 - 540 = 27 more vacuums sold.
Now divide the increase amount by the original high and multiply that by 100 to get the percentage:
27 / 540 = 0.05
0.05 * 100 = 5% Increase.