We know that the sum of the internal angles of a triangle is 180°. This is:
[tex]m\angle A+m\angle B+m\angle C=180\degree[/tex]
Where:
m∠A = 46°
m∠C = 90°
So:
[tex]\begin{gathered} 46\degree+m\angle B+90\degree=180\degree \\ 136\degree+m\angle B=180\degree \end{gathered}[/tex]
And solve for m∠B:
[tex]\begin{gathered} 136\degree+m\angle B-136\degree=180\degree-136\degree \\ m\angle B=44\degree \end{gathered}[/tex]
Answer: B. 44°
