questions are on attachment!
#1) Using the given info, $\displaystyle y=kz$ and $\displaystyle y=\frac{k}{\sqrt{r}}$ for some constant k. The question said that the constant of proportionality is the same for both and that this value is 10. Thus $\displaystyle y=10z$ and $\displaystyle y=\frac{10}{\sqrt{r}}$. You can solve each question using basic algebra from here.