we begin with 80 slices/day at $2.00/slice
then, we construct a table showing the decrease in unit sales coupled with the increase in unit price
the result is:
80s/d x $2.00/s = $160/d
75s/d x $2.25/s = $168.75/d
70s/d x $2.50/s = $175.00/d
65s/d x $2.75/s = $178.75/d
60s/d x $3.00/s = $180.00/d
55s/d x $3.25/s = $178.75/d
50s/d x $3.50/s = $175.00/d
so, maximum revenue will be reached at 60 slices per day times $3.00 per slice, and that number will be $180.00 per day