Algebra 2 Common Core

$k = \frac{r-15}{2}$
Our goal is to isolate k. To do this we first need to subtract 15 from both sides and add 2k to both sides: r-2k = 15 r-15-2k = 0 r-15 = 2k We then need to divide both sides by two to get k by itself: r-15 = 2k $k = \frac{r-15}{2}$