5gz when g is 3 and z is -4?

To evaluate the expression (5gz) when (g = 3) and (z = -4), substitute the values into the expression:

[ 5 \cdot 3 \cdot (-4) = 5 \cdot 3 = 15 \quad \text{and then} \quad 15 \cdot (-4) = -60. ]

Thus, (5gz = -60).