Points $R$, $S$, and $T$ are on a number line. The midpoint of $\overline{RS}$ is $3$ units from $R$ (since $RS = 6$, the midpoint is at $\frac{6}{2} = 3$ from $R$).

The distance from $S$ to $T$ is $20$. The midpoint of $\overline{RS}$ is on the same side as $R$, so the distance from the midpoint to $T$ is:

$3 + 20 = 23$