A skating rink charges $6.25 for skate rentals for people of all age groups. If C
represents the total number of children who rented skates and A represents the
total number of adults who rented skates, which expression best represents the
total money earned by the skating rink for the rental of skates?
a. 6.25 + a + c
b. 6.25a + 6.250
c. 6.25 (a + c)
d. 6.25a X 6.250