Answer:
39.9
Explanation:
A good trick to remember is SOH CAH TOA.
Sine = Opposite / Hypotenuse
Cosine = Adjacent / Hypotenuse
Tangent = Opposite / Adjacent
Here, we're given an angle and the opposite side, and we want to find the adjacent side. So we need to use tangent.
tan 31° = 24 / x
x = 24 / tan 31°
x ≈ 39.9