Question 1052456
Making a diagram would help.


h, how high against the wall to start
x, the movement distance along the ground and down the wall
Pythagorean Theorem Formula for right triangle
10, hypotenuse for before and after


Initially:   {{{h^2+6^2=10^2}}}
New:  {{{(h-x)^2+(6+x)^2=10^2}}}


Nonlinear system in the two variables h and x.

That should get you well-started.


--
{{{system(h=8,highlight(x=2))}}}