Every morning halle goes to school with a 1 literwaterbottle she drinks 1/4 of the bottle before school starts and 2/3 of the rest before lunch. how many mililiters are left in the bottle lunch?

To get the amount that remains by lunch time we proceed as follows:
Total amount of water Halle drinks is:
(1/4+2/3)
to add we put the fraction under the same denominator by multiplying the denominators
=4*3=12
thus
1/4+2/3
=(3+2*4)/12
=(3+8)/12
=11/12
The fraction water in the bottle when full is 1/1
thus the remaining amount will be:
1/1-11/12
=1/12
Answer is 1/12
given that 1 liter= 1000ml, the remaining amount will be
1/12*1000
=83 1/3 milliters

The correct answer is -20y