Lake Titicaca is officaly the largest lake in South America.
Explanation: Lake Maracaibo is actually larger in size; however, it cannot officially be classified as a lake since it is connected to the Caribbean Sea.
If you need to know how many she had left then... 2/5 x 1/3 = 6/15. Sorry if I came out rude, but I hope I helped! Let me know if you need anything else!