Margo can purchase tile at a store for $0.99 per tile and rent a tile saw for $36. At another store she can borrow the tile saw for free if she buys tiles there for $1.59 per tile. How many tiles must she buy for the cost to be the same at both stores? Margo must buy ??? tiles for the cost to be the same at both stores.

If she buys 60 tiles, the cost at both shops is the same.
If she buys less than 60 tiles, then the second shop is cheaper.
If she buys more than 60 tiles, then the first shop is cheaper.
Explanation:
Let the number of tiles be
x
At the first shop: Cost =
$
0.79
×
x
+
$
24
=
0.79
x
+
24
At the second shop: Cost =
$
1.19
×
x
=
1.19
x
If the cost is the same:
1.19
x
=
0.79
x
+
24

←
solve for x
1.19
x
−
0.79
x
=
24
0.4
x
=
24
x
=
24
0.4
x
=
60
tiles
If she buys less than 60 tiles, then the second shop is cheaper.
If she buys more than 60 tiles, then the first shop is cheaper.