Note that a straight is always 180 degrees
So the sum of the angles :
[tex]\begin{gathered} m\angle1+m\angle2+m\angle3=180 \\ \end{gathered}[/tex]
But it is also given that m<3 is 90 degrees
So the equation will be :
[tex]\begin{gathered} m\angle1+m\angle2+90=180 \\ m\angle1+m\angle2=90 \end{gathered}[/tex]
So the answer is Choice C. m<1 + m<2 = 90
