23)
A health club charges $150 per month for each member, plus an hourly rate of $5
for the use of the club's facilities. The function shown below can be used to deter-
mine the cost in dollars per month for the use of this health club's facilities.
f(h) = 150 + 5h.
Janine used the club's facilities in October, November, and December. If she paid
$300 in October, $380 in November, and $330 in December, how many total hours
did she spend at the club during these three months?