The mean and variance of 7 observations are 7 and 18 respectively. If 5 of the observations are 2, 4, 10, 11, 13 and the remaining observations are x…

The mean and variance of $\displaystyle 7$ observations are $\displaystyle 7$ and $\displaystyle 18$ respectively. If $\displaystyle 5$ of the observations are $\displaystyle 2$, $\displaystyle 4$, $\displaystyle 10$, $\displaystyle 11$, $\displaystyle 13$ and the remaining observations are $\displaystyle x$ and $\displaystyle y$, then $\displaystyle x y$ is equal to \_\_\_\_.