pythagorean theorem
legnth of lader is hypotonuse (leaning against wall and wall is one leg and distance from wall to bottom of ladder is other leg)
so
a^2+b^2=c^2 where a and b are legs and c=hypotonuse
a=8
c=24
8^2+b^2=24^2
64+b^2=576
subtract 64
b^2=512
square root both sides
22.62
round to tenth
22.6
answer is 22.6 ft