Let a, b, c ∈ N and a < b < c. Let the mean, the mean deviation about the mean and the variance of the 5 observations 9,25, a, b, c be 18, 4 and…

Let $\displaystyle \mathrm{a}, \mathrm{b}, \mathrm{c} \in \mathrm{N}$ and $\displaystyle \mathrm{a}<\mathrm{b}<\mathrm{c}$. Let the mean, the mean deviation about the mean and the variance of the $\displaystyle 5$ observations $\displaystyle 9,25, \mathrm{a}, \mathrm{b}, \mathrm{c}$ be $\displaystyle 18$, $\displaystyle 4$ and $\displaystyle \frac{136}{5}$, respectively. Then $\displaystyle 2 \mathrm{a}+\mathrm{b}-\mathrm{c}$ is equal to $\displaystyle \_\_\_\_$