Answer
$$D = T - pm$$
Work Step by Step
To solve this equation for $D$, we need to isolate $D$ to one side of the equation.
To isolate $D$, we need to get rid of everything else on the side of the equation with the $D$ term. The term $pm$ is added to $D$, so we do the opposite operation to both sides of the equation to get rid of $pm$ and still keep the equation equal on both sides.
If we subtract $pm$ from both sides of the equation, we get $D$ by itself:
$$D = T - pm$$