Answer:
I have to say, I was a bit stumped on this one for some reason, but I believe your answer is y^2.
Explanation:
All four variables , (14, 15, y^2, & y^4) should all have a common denominator, but I only see similarities in y^2 with y^4 and 14 with 15, but the y's can be understood ones. Multiply your common variables and get y^2. Could someone check me in that though?