Tom starts a lawnmowing business. before he can begin, he purchases a new lawnmower. each weekend he mows the same number of lawns and earns the same amount of money. write an equation to show how much money he's earned at any week. x y week profit in dollars 1 –90 2 –30 3 30 4 90 a. y = 60x – 90 b. y = 60x – 150 c. y = 90x + 150 d. y = 60x