b. } 5-3 & =2018 M & =(2 x^2-2 x-31)/(}end{aligned)

The equation $5=3=2$ is incorrect as it suggests that three different numbers are equal to each other, which is not possible. Therefore, we will focus on solving the expression for $M$.<br /><br />Given:<br />\[ M = \frac{20 + 8}{\sqrt{x^2 - 2x - 31}} \]<br /><br />Simplify the numerator:<br />\[ 20 + 8 = 28 \]<br /><br />So the expression becomes:<br />\[ M = \frac{28}{\sqrt{x^2 - 2x - 31}} \]<br /><br />Therefore, the solution for $M$ is:<br />\[ M = \frac{28}{\sqrt{x^2 - 2x - 31}} \]