Two stores

Question

Margo can purchase tile at the store for $0.99 per tile and rent a tile saw for $21. At another store she can borrow the tile saw for free if she buys tiles there for $1.29 per tile. How many tiles mat she buy for the cost to be the same at both stores?

Answer 1

Let x = the number of tiles.  At the first store, Margo's cost is:

 

Cost = ($0.99)x + $21

 

At the second store, her cost is:

 

Cost = ($1.29)x

 

When the cost is the same:

 

($0.99)x + $21 = ($1.29)x

 

$21 = (0.30)x

 

Solve for x

Answer 2

We have 2 equations for cost:

 

c = .99t + 21

c = 1.29t

 

If the cost is the same, then we can set the 2 equations equal to each other:

 

.99t + 21 = 1.29t

21 = .30t

70 = t

 

The cost will be the same when she buys 70 tiles.