Answer:
 The distance of the base of the wall to the ladder is 5 Feet .
Explanation:
As given
A 13 foot ladder is leaning against a wall. 
If the point where the ladder meets the wall is 12 feet above the ground.
 As shown in the figure given below.
Now by using the pythagorean theorem
Hypotenuse² = Perpendicular² + Base²
AB² = AC² + BC² 
As
AB = 13 foot
AC = 12 foot
Put in the above
13² = 12² + BC² 
169 = 144 + BC² 
BC² = 169 - 144

BC = 5 Feet 
Therefore the distance of the base of the wall to the ladder is 5 Feet .