Answer
m$\angle$3=110$^{\circ}$
Work Step by Step
Angles 13 and 15 are corresponding angles so they are congruent.
m$\angle$13=m$\angle$15=70$^{\circ}$
Angles 15 and 3 are same side exterior angles so they are supplementary.
m$\angle$15+m$\angle$3=180
70+m$\angle$3=180
m$\angle$3=110$^{\circ}$