Answer
$m\angle EFG=69$
$m\angle GFH=111$
Work Step by Step
Use the definition of a linear pair:
$m\angle EFG+m\angle GFH=180$
Substitute:
$(2n+21)+(4n+15)=180$
Combine like terms:
$6n+36=180$
Subtract 36 from each side:
$6n+36-36=180-36$
$6n=144$
Divide each side by 6:
$6n\div6=144\div6$
$n=24$
Substitute to find the measures:
$m\angle EFG=2n+21=2(24)+21=48+21=69$
$m\angle GFH=4n+15=4(24)+15=96+15=111$
