Using the law of cosine:
Cosine(angle) = Adjacent leg / Hypotenuse
You are given the angle, and the adjacent leg and need to solve for X, which is the hypotenuse.
Using the formula above you have:
Cosine(58) = 17 / x
Solve for x by dividing 17 by cos(58)
x = 17 / cos(58)
x = 32.08
Is= equals sign
times= multiplication
So y equals 15 times x
y= 15 * x
y= 15x
ANSWER: y= 15x (bottom choice)
Hope this helps! :)