## Elementary Geometry for College Students (5th Edition)

m $\angle$ 5 = 109$^{\circ}$
m$\angle$3 = 71$^{\circ}$ By the Interior Angles Postulate: m$\angle$3 + m$\angle$5 = 180∘ Substitute the value of 71 into the equation. 71 + m$\angle$5 = 180 Subtract 71 from 180 Simplify. m$\angle$5 = 109$^{\circ}$