The correct answer is 15.
This is because the relationship between x and y is y=3x, as can be verified by the other points in the table.
3 = 3(1), 6 = 3(2), 24 = 3(8).
When we plug in 5 for x into our equation, we get 3(5), which equals 15.
Therefore, your answer is 15.
Hope this helps!