Question 194408
1. Using the Pythagorean theorem:
{{{c^2 = a^2+b^2}}} the hypotenuse is side c (x in this problem) and a = 12 and b = 9, so...
{{{c^2 = 12^2+9^2}}}
{{{c^2 = 144+81}}}
{{{c^2 = 225}}} Take the square root of both sides.
{{{c = 15}}} 
The length of X is 15 units.
2. The answer to this question is...it depends on the length of the ladder, a critical piece of information that is not provided.