Answer
$y^{7}$
Work Step by Step
We are given the expression $(y^{7})^{5}$.
Recall that an exponential expression consists of a factor, known as the base, and an exponent. The number of times that the base is multiplied is indicated by the value of the exponent.
Therefore, $y^{7}$ is the base of the exponent 5.
Multiplied out, $(y^{7})^{5}=(y^{7}\times y^{7}\times y^{7}\times y^{7}\times y^{7})$