A, B and C together hold a pasture for which they pay a rent at the rate of $ 160 per month. They put on it 70, 50 and 40 cows respectively. A sells (2 / 7) th of his stock to B after 4 months and further 3 months later C sells (2 / 5) th of his stock to A. How much of the rent should A pay in one year?