y represents the total number of bottles produced in the given time in seconds, which is x. When x=1, y=20, This means that each second the machine can make 20 soda bottles. Each minute is 60 seconds, so when x=60, y=20*60 =1200 soda bottles.
It could sometimes be proportional. The reasoning here is that if all the items have different prices it won't be, however if the items you are ordering all have the same price they will be!
