To find the answer to this question we would have to find the Least Common Denominator. We have 1/2, 2/5, and 1/10. What multiples do these numbers have in common.
2, 4, 6, 8, 10
5, 10, 15, 20, 25
10, 20, 30, 40, 50
10 is our LCD so that's the answer.