Answer:
the answer is 3.5
Explanation:
1. the total is 4
2.each mug = .5 of a litre
3.jane drinks 3 mugs which=1.5
4.she drinks 1.5 litres which is 3.5 of the whole bottle
5.so the remaining will be 3.5 which is what remains after she drank 1.5 litres of the whole bottle