2/6 + 1/5
It requires a common denominator. Common means it's the same on both terms.
One sure way to determine a common denominator is to multiply the two together.
In this case, 6 • 5 = 30 is one common denominator. There are others.
2 1
––– + ––– =
6 5
10 6 16 8
––– + ––– = ––– reduces to –––
30 30 30 15
.