Answer
y=9
Work Step by Step
The diagram shows that $\angle BDR$ is a right angle.
The Angle Addition Postulate tells us that $\angle BDJ$ and $\angle JDR$ are complementary.
$(7y+2)+(2y+7)=90$
combine like terms
$9y+9=90$
subtract 9 from each side
$9y+9-9=90-9$
$9y=81$
divide each side by 9
$9y\div9=81\div9$
$y=9$
