Let make the denominators of all the fraction same, so that we can compare just the numerator to arrive at the answer.
34=3×254×25=75100
52=5×502×50=250100
825=8×425×4=32100
75=7×205×20=140100
Now we can compare the largest and smallest by looking at the numerators.
So the smallest fraction is 825 and the largest fraction is 52