Remember that the sum of the interior angles is 180. Then, we have the following equation:
[tex]55^{\circ}+65^{\circ}\text{ + }\angle M\text{ = 180}[/tex]
This is equivalent to:
[tex]120^{\circ}\text{ + }\angle M=180^{\circ}[/tex]
solve for M-angle:
[tex]\text{ }\angle M=180^{\circ}-\text{ 120}^{\circ}=60^{\circ}[/tex]
Then, te correct answer is :
[tex]\text{ }\angle M^{}=60^{\circ}[/tex]
