Show your work please
john wants to know the square footage of his living room in order to lay new hardwood floors. The living room has vertices at the coordinates (1,5) (11,3) (3,15) (13,13). If each unit one the coordinate plane is one square unit, then how many square feet of flooring must john buy in order to cover his entire living room?

extension questions:
1) john wants to buy 10% more flooring than his room requires to account for errors. If boxes of flooring cover 20 square feet, how many boxes will john need in order to account for errors in measurement?
2) if hardwood flooring costs $3.98 per square foot, what will it cost john to put new floors in his living room?