Exercise 9 Page 165

Both angles are between the lines and on the same side of the transversal. Therefore, the angles can be classified as consecutive interior angles. According to the Consecutive Interior Angles Converse, if the angles are supplementary, the lines are parallel. We can therefore write the equation. x+73=180 Let's solve this equation.

x + 73 = 180

SubEqn

LHS-73=RHS-73

x = 107

When x=107, we have m ∥ n.