URGENT

$(12$ points$)$ You are assigned the task of determining the number of machines assigned to a

worker in a manufacturing line. It takes the worker $2$ min to walk in between each machine

and then $10$ min to load each machine. Once loaded the machine takes $20$ min to process the

loaded part. The cost to run each machine is $$\frac{30}{h}r.$ Each worker earns $$\frac{12}{h}r.$ How many

machines should be assigned to each worker?