look at how many two coin combinations are given by 10p, 10p, 10p, 20p, 20p, 50p. to find out how many give greater than or equal to 40p, look at the them and see how many pairs you can make with them. e.g. one of the pairs is 20p and 50p, 20p has a probability of 2/6 and 50p has a probability of 1/6. once you find the pairs, work out the probability of getting each one individually. remember you're not putting them back in the box so the amount of coins in the bag changes, hence conditional probability.