A can do a work in 15 days and B in 20 days. They work on it together for 4 days, then the fraction of the work that is left is -

অপশনসমূহ
সঠিক উত্তর চিহ্নিত
ক 1/4
খ 1/8
গ 1/15
ঘ 8/15