Question 1161392
Angle measures, x and y


y=2(x+3), "one of them" being y.


x+y=90, the two angle measures sum to 90, for them to be "complementary".


Substituting,
{{{x+2(x+3)=90}}}


{{{x+2x+6=90}}}
{{{3x=90-6}}}
{{{3x=84}}}
{{{highlight(x=28)}}}
-
{{{highlight(y=62)}}}