Tanner wants to fill his swimming pool using two hoses, each of which sprays water at a constant rate. Hose AA fills the pool in aa hours when used by itself, where aa is a positive integer. Hose BB fills the pool in bb hours when used by itself, where bb is a positive integer. When used together, Hose AA and Hose BB fill the pool in 66 hours. How many different possible values are there for a? a) 5
b) 6
c) 9
d) 10
e) 12