Question 306424
Let the first ladder be the 30' ladder. 
The base is (0,0), then end at (10,30).
The equation that describes this ladder is
{{{y=3x}}}
The second ladder's base is (10,0) and the end is at (0,20).
The equation that describes this ladder is
{{{y=20-2x}}}
Find the intersection point.
{{{3x=20-2x}}}
{{{5x=20}}}
{{{x=4}}}
When {{{x=4}}}, then
{{{y=3x=3(4)=12}}}
They intersect 12' above the ground.
{{{ drawing( 300, 300, -2, 12, -5, 45, grid(1),green(line(0,0,10,30)),
green(line(10,0,0,20)),circle(4,12,0.3)) }}}