THE TIRE PROBLEM

Milena wanted to drive out west to visit her friend and later return home. The whole trip (round trip) is 2,700 miles. Milena has 4 tires that go 1,200 miles each before they wear out. How many tires (minimum) does she need to make the round trip?

*adapted from Sheila Tobias' Overcoming Math Anxiety.

(Explain how you would use the number of tires that you got for your answer). For the answer, don't look right away!