Each month, the charge for a racquet club membership consists of a flat fee of $15, plus $3 each time equipment is rented. Which of the following equations represents the total monthly charge, M(r) dollars,
for the membership as a function of the number of times equipment is rented, r ?
A. M(r) = 3(15)r
B. M(r) = (3 + 15)r
C. M(r) = 3r + 15
D. M(r) = 15r +3
E. M(r) = r +3+15

The table below shows the approximate masses of a dust particle and a grain of pollen. dust particle 0.000000778 g grain of pollen 0.00000000155 g the mass of a dust particle can be estimated and written in the form a × 10^b, where a = 8 and b = the mass of a grain of pollen can be estimated and written in the form a × 10^b, where a = 2 and b = based on the estimates, the mass of a dust particle is approximately blank times larger than the mass of a grain of pollen.