Help pls pls pls.

Problem melissa is her dad build a walkway in their backyard. the walkway will be 54 feet long and 1.5 feet wide. the local hardware store sells tiles which are 1.5 by 1.5 feet and come in boxes of 12. how many boxes of tiles do they need?

The graph represents the gallons of water in a water tank with respect to the number of hours since it was completely filled

Math it's appreciated. (picture provided)