The chef knows that 6 cooks can make 36 cakes in two hours. But, the chef needs 57 cakes. How many cooks does he need

We need to find out 1) how many cakes does 1 cook make in two hours: 36:6=6; 2) how many cakes does one cook make in one hour: 6:2=3; 3) if the chef needs 57 cakes to be made in one hour, we can find out the number of cooks he needs that way: 57:3=19. So the chef needs 19 cooks to do this job.