#### Answer

$x=-t-r$.

#### Work Step by Step

In order to isolate x, we first cancel out addition by subtracting one on both sides. This leaves us with the following: $-1=\frac{x+r}{t}$. We cannot just subtract by r on both sides because it, like x, is being divided by t. In order to cancel out division, we use multiplication, so we multiply both sides by t to get that $x+r=-t$. We now cancel out the addition by subtracting r on both sides, giving us a final answer of $x=-t-r$.