Walter gets up at 6:30 a.m., catches the school bus at 7:30 a.m., has 6 classes that last 50 minutes each, has 30 minutes for lunch, and has 2 hours additional time at school.  He takes the bus home and arrives at 4:00 p.m.  How many minutes has he spent on the bus?
$\text{(A)}\ 30 \qquad \text{(B)}\ 60 \qquad \text{(C)}\ 75 \qquad \text{(D)}\ 90 \qquad \text{(E)}\ 120$
There are $4\frac{1}{2}$ hours from 7:30 a.m. to noon, and $4$ hours from noon to 4 p.m., meaning Walter was away from home for a total of $8\frac{1}{2}$ hours, or $8.5\times 60 = 510$ minutes.
Tallying up the times he was not on the bus, he has $6\times 50 = 300$ minutes in classes, $30$ minutes at lunch, and $2\times 60 = 120$ minutes of "additional time".  That is a total of $300 + 30 + 120 = 450$ minutes that Walter was away from home, but not on the bus.
Therefore, Walter spent $510 - 450 = 60$ minutes on the bus, and the answer is $\boxed{B}$