The ladder is leaning against the wall, the information you're given, being that she's 5 feet up and 3 feet from the wall shows that every 3 feet she moves on the ladder, she moves up 5 feet, the ladder is 15 feet away from the wall so 15/3 is 5 multiply that by 5 to get the total length of the ladder, which is 25. Then use Pythagorean theorem (A^2 + B^2 = C^2) 15 would be the A or B value because it's the distance from the wall, the C value, or the hypotenuse would be 25 because it's the total length of the ladder, replace the variables so you get A^2 + 15^2 =25^2 then square the integers, and get A^2 + 225 = 625, subtract 225 from each side and you're left with A^2 = 400, take the square root of each side (√A^2 = √400) and you're left with your answer of A=20
