The value of g(5) is -15.
In order to solve given a x value in a piecewise function, you first need to determine which part of the function to use. Since the stipulations say to use the bottom one if x > 4 and 5 is in fact greater than 4, then we must use the bottom equation. So, we plug 5 into that equation to find the answer.
g(x) = -3x
g(5) = -3(5)
g(5) = -15
