Question 329118
{{{A=(1/2)bh=30}}}
{{{(1/2)b(b+4)=30}}}
{{{b^2+4b=60}}}
{{{b^2+4b-60=0}}}
{{{(b+10)(b-6)=0}}}
Only positive b solutions make sense here.
{{{b-6=0}}}
{{{b=6}}}
Then 
{{{h=6+4=10}}}