If someone had 1pound and then they brought 2 cartons of drink and got 30p change how much did each carton of drink cost?

If someone had £1 and received 30p in change after buying 2 cartons of drink, they spent 70p (£1 - 30p = 70p). Since they bought 2 cartons, the cost of each carton would be 70p divided by 2, which is 35p. Therefore, each carton of drink cost 35p.