To solce the problem above, you must apply the proccedure shown below:
1. You have the following expression given in the exercise:
y^-3
2. The negative sign in the exponent 3, means that the the base y and the exponent 3 are in the denominator. Keeoing this on mind, you have:
y^-3=1/y^3
Therefore, the answer is: 1/y^3