Algebra Puzzle – Challenge 50

Challenge:

If 11 workers can build 11 cars in 11 days, then how many days would it take 7 workers to build 7 cars?

A- 7

B- 9

C- 11

D- 14

E- 18

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If 11 workers can build 11 cars in 11 days, then 11 workers can build one car per day. (Find the rate of cars per day)
If, 11 workers can build one car per day, then, one worker can make a car in 11 days. (Each worker can build (frac{1}{11}) of a car per day. So, it takes 11 days for a worker to make a car)
If one worker can make a car in 11 days, then it takes 77 days for a worker to make 7 cars. With this rate, 7 workers can make 7 cars in 11 days. Why?

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