Question 4Emma earns $a$ dollars per hour for the first 6 hours of her shift and $b$ dollars per hour for each hour after that. If she works 12 hours in one shift, what is her average hourly wage?$\frac{a+b}{3}$$\frac{a+2b}{2}$$6a+6b$$\frac{a+b}{2}$None of the above