Melinda and Shirley worked together to make hamburger patties. Shirley worked for 1 hour and 45 minutes, Melinda worked for 45 minutes, and they split their earnings according to the amount of time each spent working. Melinda’s hourly rate, however, is twice that of Shirley’s. If the two together earned $48.75, what was Shirley’s hourly rate?

a. $15

b. $20

c. $25

d. $30

e. $35