Answer: ≈117.15375m (if you're expected to round make sure you do so!)
Explanation: Because this a right triangle, you can apply the pythagorean theorem which is a^2 + b^2 = c^2. a and b can be any side except the hypotenuse (the one across from the 90° angle). You take 90^2 + 75^2 = c^2. This equals 13,725 after that you can take the square root of it and you're left with ≈ 117.15375m
Hope this helped! :)