Answer:
They are both right becuase if you just take away 1 from 20 and 10 you get 2 and 1. For the 4:2 one take away 1 and mutiply by 2 equalling 4:2 but they are still the same thing.
Step-by-step explanation:
For the range:
5, infinity
1 day use 4 bags
? day use 1/2 bag
Cross multiply
(1•1/2)/4= 1/2•1/4= 1/8 of the day
In 1/8 of the day 1/2 of bag of milk will be used.