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Set up, but do not solve the following word problem. Two private airplanes travel toward each other from cities that are 780 km apart at speeds of 190 km/hr and 200 km/hr. They left at the same time. In how many hours will they meet?
Foundations

What is the formula for distance?

Answer:

The formula for distance is d=rt where r is the rate and t is the time.

Solution:
Step 1:

The distance formula for the plane traveling 190km/hr is $190t=d$.

Step 2:

The other plane starts off 780km away from the first plane. So, this plane's distance is 780d where d is the distance of the first plane.

So, the distance formula for this second plane is $200t=780d$.

Step 3:

Now, adding these two equations together, we get $390t=780$. So, $t=2$ hours.

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