Ken studies math for 45 minutes each day. In 15 minutes, he completes two math problems while watching music videos. The number of questions worked, q, is proportional to the amount of time spent, t.
Which equation can be used to show the rate, r, of problems worked per minute for Ken?
A. 45r=15
B. 45r=2
C. 15=2r
D. 2=15r
