store a: $25 for 45 minutes
store b: $30 for 1 hour
store c: $45 for 1.5 hours
store d: $80 for three 1 hour lessons
julie needs to have swim lessons for her son. there are four different stores that offer swim lessons. which one is the best deal?

A). $25/ 0.75 hr = $33.33 per hour

B). $30 / 1 hr = $30 per hour

C). $45 / 1.5 hr = $30 per hour

D). $80 / 3 hr = $26.67 per hour

Comparing only the unit prices for swim lessons, Store 'D' offers
lesson time for the lowest price.

But there are several other factors besides price that ought to figure
into the decision.  For example:

-- location of the lessons;  This greatly affects the total time
and expense just to get there before and get home after.

-- quality of the instructors;  How much experience do they have ? 

-- class size;  Will Julie's son get one-on-one lessons,or will he be
one out of 162 swimmers in the pool at the same time ?

-- lesson content;  Will he get ten minutes of "Do this !" followed by
50 minutes of going over and over it alone in a corner of the pool ?

"Best Deal" means not only spending the least, but getting the most
at the lowest cost.

Polar coordinates is 8,9