## Geometry: Common Core (15th Edition)

$m\angle1=48$ $m\angle2=42$
Using the Angle Addition Postulate and the definition of a right angle: $m\angle1+m\angle2=90$ Substitute the given expressions and solve for y. $4y+(2y+18)=90$ Combine like terms. $6y+18=90$ Subtract 18 from each side and simplify. $6y+18-18=90-18$ $6y=72$ Divide each side by 6 and simplify. $6y\div6=72\div6$ $y=12$ Substitute for y and simplify to find $m\angle1$. $m\angle1=4y=4(12)=48$ Substitute for y and simplify to find $m\angle2$. $m\angle2=2y+18=2(12)+18=24+18=42$