Question 1092570
<br>If the fraction is to have a denominator that is a multiple of 5, and the fraction must be equivalent to 1/2, then the possible denominators are the multiples of 10:  10, 20, 30, 40, ....<br>
5/10 is a fraction with a prime numerator and a denominator that is a multiple of 5.<br>
But any other fraction equivalent to 1/2 and with a denominator that is a multiple of 5 would just be the fraction 5/10, multiplied top and bottom by some integer.<br>
But that would make the numerator not prime.  So not only is 5/10 and answer to the problem, it is the ONLY answer.