For this case, we observe that both the numerator and the denominator of the fraction are multiples of the following numbers:
2,3,6
Then we observe that the biggest common factor is 6.
Taking out common factor we have:
36/90 = ((6) / (6)) * (6/15) = 6/15
Answer:
the greatest common factor that could be used to reduce 36/90 is:
6