Answer
$y=45/16$
Work Step by Step
"y vary directly as x, and inversely as $m^2$ and $r^2$" can be written as:
$y=\frac{kx}{m^2r^2}$
With the information regarding the value of y, x, m and r, we are able to find constant k.
$\frac{5}{3}=\frac{k}{2^2*3^2}$
$3k=5*4*9=180$
$k=60$
Then, we can use this k constant and the information of another set of x, m and r to find y.
$y=\frac{60*3}{1^2*8^2}=\frac{180}{64}=45/16$