jmc

Factoring the squares out of $40\cdot 9$ gives us $2^2\cdot 3^2\cdot 10=6^2\cdot 10$. Thus, the numerator is $6\sqrt{10}$.

The denominator is $7$, because $7^2=49$. So our answer is $\boxed{\frac{6\sqrt{10}}{7}}$.