If 3 <= p <= 10 and 12 <= q <= 21, then find the difference between largest and smallest possible values of p/q.
since it is 3/12 and 10/21 we find the common denominator to get 63/252 and 120/252 we find that it os (120-63)/252=57/252=19/84 so we get 19/84 as the final answer
