A ladder 15 m long can so be placed that it will reach a point on a wall 10 m above the ground. By tipping it back without moving its feet, it can be made to reach a point on another wall 8 m above the ground. What is the horizontal distance between the walls?

d1^2 = 225-100 = 125

d2^2 = 225 - 64
distance

between = d1+d2

add because the walls are in front of and in back of the fireman:)