Difficult# Simplify Expression

MVCALC-OYMZJF

Simplify the following expression:

$$\frac{\iint_R f(xy)dxdy}{\int_1^2 f(u)du}$$

...where $R$ is the region enclosed by $xy=1, xy=2, y=x, y=4x$ in the first quadrant, $f$ is a continuous function that is strictly positive on $R$.