Two children at a time can play pairball.  For $90$ minutes, with only two children playing at time, five children take turns so that each one plays the same amount of time.  The number of minutes each child plays is
$\text{(A)}\ 9 \qquad \text{(B)}\ 10 \qquad \text{(C)}\ 18 \qquad \text{(D)}\ 20 \qquad \text{(E)}\ 36$
There are $2 \times 90 = 180$ minutes of total playing time. Divided equally among the five children, each child gets $180/5 = \boxed{\text{(E)}\ 36}$ minutes.