Question 898169
First step, make a diagram. 
{{{drawing(300,300,-10,10,-10,10,line(-10,-5,5,-5),locate(-2,-3.5,B),locate(2,-3.5,A),line(5,-5,5,10),blue(line(0,-5,5,5)))}}}
The ladder is in blue.
The wall and ground are in black.
{{{A+B=180}}}
{{{B=20+3A}}}
Substitute,
{{{A+(20+3A)=180}}}
{{{4A+20=180}}}
{{{4A=160}}}
Now solve for {{{A}}} and then work backwards to solve for {{{B}}}