Joint products and by products

A company manufactures two main products, j and k and the by product L .The product has a net realisable value 2 dollars per litre. The following information relates to last month ,when there were no opening inventories. Production j was 50000litres and sales 45000litres, production k was 40000 and sales wer 30000litres and by product L production was 10000litres .joint cost last month were 290000 :company policy is to apportion joint costs on a physical measure basis and to treat the net realisable value of the by product as a deduction from the cost of the main products. Question is What was the cost value of last month closing inventory of product j?