When the ladder is set against the house originally, it forms a right triangle with the house wall and the ground.
The ladder (hypotenuse) is 30 feet and the height it reaches is 24 feet. We can use the Pythagorean theorem to find the distance of the ladder from the base to the top of the house wall.
Let x be the distance that the ladder moves horizontally away from the house.
Using the Pythagorean theorem:
(24 + 10)^2 = x^2 + 30^2
34^2 = x^2 + 900
1156 = x^2 + 900
x^2 = 1156 - 900
x^2 = 256
x = β256
x = 16 feet
So, when Alexander pulls the ladder 10 feet farther from the house, it will reach 16 feet up the side of the house.