8/2z=15/60 .solve proportion.
\(\dfrac{8}{2z}=\dfrac{15}{60}\\ \dfrac{4}{z}=\dfrac{1}{4}\\ z=16\)
\(\frac{8}{2z}=\frac{15}{60}\ \ \ \ \ |cross\ multiply\\\\2z\cdot15=8\cdot60\\\\30z=480\ \ \ \ |divide\ both\ sides\ by\ 30\\\\\boxed{z=16}\)
