## Geometry: Common Core (15th Edition)

$x=2.5$ $m\angle1=30$ $m\angle2=30$
Angles 1 and 2 are in corresponding positions relative to the 4 angles created when the transversal intersects with line r and the 4 angles created when the transversal intersects with line s. The Converse of the Corresponding Angles Theorem tells us that the lines are parallel when $\angle1\cong\angle2$, or, by the definition of congruency, when $m\angle1=m\angle2$. Write and solve an equation to find the value of x when the lines are parallel. $m\angle1=m\angle2$ $40-4x=50-8x\longrightarrow$ substitution $40+4x=50\longrightarrow$ addition property of equality $4x=10\longrightarrow$ subtraction property of equality $x=2.5\longrightarrow$ division property of equality Substitute to find the measue of each angle. $m\angle1=40-4x=40-4(2.5)=40-10=30$ $m\angle2=50-8x=50-8(2.5)=50-20=30$