Answer:
Margo must purchase 30 tiles for the cost to be the same at both stores.
Explanation:
By analyzing the "real-world" problem, we can convert the words into two algebraic equations.
Step 1:
Store 1:
"$0.59 per tile and rent a tile saw for $18."
y = 0.59x + 18
y = the price of the tiles bought
0.59 = price of one tile
x = number of tiles
18 = the fixed cost of a saw
Store 2:
"At another store, she can borrow the tile saw for free if she buys tiles there for $1.19 per tile."
In this case, the saw is free. Thus, we don't need to add a price to the equation.
y = 1.19x
y = the price of the tiles bought
1.19 = price of one tile
x = number of tiles
Step 2:
Now that we have both equations, we can write down the equations that equate other. This formula will indicate that the equations would intersect at a certain point on the x and y values. Hence, this step will answer how many tiles are required for both stores to equal the same price.

Now solve for x:

Margo can buy 30 tiles from both stores for the cost to be equal.
You might ask, "But what about the price?" This is where we solve for y; this variable will answer how much the tiles would cost at 30 tiles. So, we can take the answer for "x" and plug it into any of the two equations.

For this equation, all you have to do is multiply both numbers to get your answer.

Bottom Line:
Therefore, Margo can buy 30 tiles for the cost to be same at both stores at $35.70.