Question 106304
The ladder against the wall makes a right triangle.
The hypotenuse, H, is the ladder length, 25 feet.
One side of the triangle, {{{L[1]}}} is 7 feet. 
What is the other length, {{{L[2]}}}? 
From Pythagorean theorem,
{{{L[1]^2+L[2]^2=H^2}}}
{{{7^2+L[2]^2=25^2}}}
{{{49+L[2]^2=625}}}
{{{L[2]^2=576}}}
{{{L[2]=14}}}

The ladder will be 14 feet away from the wall. 
You probably want to move it a little closer before you take that first step.