Answer:
v = 25.98
Explanation:
You could do this a number of ways. Some are much longer than others. The shortest way is to use the tangent.
Formula
Tan(theta) = opposite / adjacent
Givens
Theta = 30o
Opposite = 15 km
Adjacent = x
Solution
tan(30) = 15 / v Multiply both sides by v
v*tan(30) = 15 Divide by tan(30)
v = 15/tan(30)
tan(30) = 0.5774
v = 15 / 0.5774
v = 25.98