The answer is -52
First you must substitute the variables

Then you must simplify

4.166 cans !
6*75 = 450 sq.ft
so approximately 4.166 cans will be required !
That would be 4 gallons every minute!
Also: I don't see a graph..? Is there supposed to be one attached?
Good luck!
25 hope it helps have a great day :)