If a ladder is leaned against a building. the bottom of the ladder is 9 feet from the building. the top of the ladder is 16 feet above the ground. what is the slope of the ladder?

Picture this as a triangle. If the ladder is the hypotenuse, or slope, of the triangle, then the base is 9 feet and the height is 16 feet. You can then use Pythagoras theorem to work out the length of the hypotenuse, which is a^2 + b^2 = c^2.
9^2 + 16^2
81 + 256 = 337
√337 = 18.358 feet
Hope this helps!