The task is to generate the correct answer for a given math problem.

Q: Problem: 20 is subtracted from 80 % of a number , the result is 60 . find the number ?

A: 100
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Q: Problem: a certain fraction is equivalent to 3 / 5 . if the numerator of the fraction is increased by 4 and the denominator is doubled , the new fraction is equivalent to 1 / 3 . what is the sum of the numerator and denominator of the original fraction ?

A: 56
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Q: Problem: a trained covered x km at 30 kmph and another 2 x km at 20 kmph . find the average speed of the train in covering the entire 3 x km .

A:
22.5
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