Dana bikes 10 miles in 50 min. at this rate how far can she bike in 90 min?

Dana would go 18 miles in 90 minutes because she is going a mile for every five minutes, so if she bikes for another forty minutes she will have biked 8 miles. This means that you would multiply 8 miles (remember its a mile per 5 minutes) by five minutes and that would give you forty. Then just add that on to the 50 minutes she has already biked.