Assume both as perfect spheres. if diameter is 1/4 then m=e/4
this is the diameter but the radius will be the same ratio too.
if you divide this you will get the same ratio
Volume of sphere= 4/3*pi*r*r*r
so take the ratio by putting the earths radius in one and moons radius in the other.
4/3*22/7*e/4*e/4*e/4:4/3*22/7*e*e*e (most of it gets divided or cancelled)