Write the expression without the fraction bar.
y to the 3rd power

y to the 7th power

For problems like this you can move the y's on the bottem up top by fliping the sign of the exponent (in this case 7 to -7) and MULTIPLYING it with EVERYTHING on top, then because of properties of multplication you can add the exponents to combine them into one term (in this case add 3 and -7 to get -4) If any of this does not make sense let me know and ill try to clarify better