Margo can purchase tile at a store for $0.59 per tile and rent a tile saw for $42. At another store she can borrow the tile saw for free if she buys tiles there for $1.19 per tile. How many tiles must she buy for the cost to be the same at both stores?

70

Step-by-step explanation:

x = number of tiles

store1(x) = 0.59x + 42

store2(x) = 1.19x

so, the question is : for how many tiles are both cost functions the same ?

0.59x + 42 = 1.19x

42 = (1.19 - 0.59)x = 0.6x

x = 42/0.6 = 70

when buying 70 tiles the cost will be the same at both stores.