Answer
-.2
Work Step by Step
We are given that $log_{b}3=.5$ and that $ log_{b}5=.7$.
The quotient property of logarithms tells us that $log_{b}\frac{x}{y}=log_{b}x-log_{b}y$ (where x, y, and, b are positive real numbers and $b\ne1$).
Therefore, $log_{b}\frac{3}{5}= log_{b}3- log_{b}5=.5-.7=-.2$.
