Answer:
So the high of the of the wall will be, 15m
Explanation:
You can use Pythagoras theorem, c^2=a^2+b^2.
Take the length of the ladder as c, the foot of the ladder as (a), and the high of the wall as (b).
So :
c^2=a^2+b^2
(17m)^2= (8m)^2+ b^2
289m^2 = 64m^2 + b^2
289m^2 - 64m^2 = b^2
225m^2 = b^2

15m = b