Answer:
70
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.