You cannot add things with units to things without units. "300mL" has a unit. "2/3" does not. Please resubmit your question where both items either have units or do not.
2/3
One third plus one third equals two thirds.
1/2 .
if you add one third and one third you get two sixths then if you divide it by 2 each you will get it back to one thirds
2/3
8L + 300ML = 8300ML or 8.3L
1/3 plus 2/3 plus 3/3 = two
8300ml
25
2/3
2/3
2 and 2 thirds
2/3
It is 4 and one third.
2 litres is 6 and 2/3 of 300 millilitres.
1/3 + 1/3 = 2/3
35