Answer
$h=-27$
Work Step by Step
We need to get the h alone. Thus, we cancel out the addition by subtracting 10 on both sides. This leaves us with the equation $h/3=-9$. In order to cancel out division, we use multiplication, so we multiply both sides by 3 to get that $h=-27$. We plug -27 in for h and confirm that our answer is, indeed, correct.
