Question 349499
{{{ABD=DBC}}}
{{{x+5y=2x+2y+3}}}
1.{{{-x+3y=3}}}
.
.
.
{{{ABD+DBC=90}}}
{{{x+5y+2x+2y+3=90}}}
2.{{{3x+7y=87}}}
From eq. 1,
{{{x=3y-3}}}
Substitute into eq. 2,
{{{3(3y-3)+7y=87}}}
{{{9y-9+7y=87}}}
{{{16y=96}}}
{{{highlight(y=6)}}}
Then from eq. 1,
{{{x=3(6)-3}}}
{{{highlight(x=15)}}}