SOLUTION: The tires on Mary's car will have to be replaced when they each have 140 000 km of wear on them. If new tires cost $100.00 each, what is the total cost of the wear on Mary's tires

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Question 1173765: The tires on Mary's car will have to be replaced when they each have 140 000 km of wear on them. If new tires cost $100.00 each, what is the total cost of the wear on Mary's tires for a year in which she drives 21 000 km?
Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
.

Use this proportion


    140000%2F100 = 21000%2Fx,


where x is the unknown value under the problem's question.


This proportion says that the miles per dollar are the same in both cases.


From the proportion, find


    x = %28100%2A21000%29%2F140000 = 15  dollars.    ANSWER

Solved.

Very simple and elegant solution (!)