This is asking for you to use the Pythagoras's theorem, which says that if you are given a height of a right triangle (h) and the length of that right triangle (L), then, the hypotenuse, or the distance between them (d), is:

Here, we are given that the height is 3m and the length is 5m. The distance, then will be given by:



So, the distance between the ladder and the bottom of the slide is 4 meters. Hope I could help! :)