Sweet treat Bakery (December 2016)

General production (based on ranking)
Number of cakes Mixing minutes
4 batches of cupcakes 80 48
1 batch of brownies 40 20
Therefore the bakery should produce 80 brownies, 30 muffins and 100 cupcakes

My question is as follows:

– How 4 batches of cupcakes are calculated and 1 batch of brownies calculated?
– Calculation logic on number of cakes and mixing minutes – do not understand the answers
– How did calculation produce 80 brownies, 30 muffins and 100 cupcakes

I have seen plenty of examples, but couldn’t follow. I would prefer calculations in detail, please