Working alone and at a constant rate, Machine A takes 3 hours to create a widget. Machine B, working alone and at a constant rate, takes x h

This makes no sense.....'A' working alone can create FOUR widgets in 12 hours......why would adding B slow it down?

Is it supposed to be  1/2 hour instead of 12 hours??????

Working alone and at a constant rate, Machine A takes 3 hours to create a widget. Machine B, working alone and at a constant rate, takes x hours to create a widget. Working together, Machine A and B take 12 hours to build two widgets. What is the value of x?

Machine B is 3X slower than machine A

3 + x = 12        x = 9