The estimated number of Amazon Prime members
in millions, $P,$ in the United States $q$ quarters since March 2015 can be represented by the equation
$$
P=7.89 q+33.73 .
$$
a. Find the estimated number of Amazon Prime members in the U.S. in March of 2017. (March 2017 is 8 quarters, 2 years, since March $2015 .$
b. Find the estimated number of Amazon Prime members in the U.S. in March of 2020
c. In what quarter will the estimated number of Amazon Prime members in the U.S. be 133 million?