Queation a,b,c

In a box containing 20 red apples and 5 green apples, 3 of the red apples are rotten and one of the green apples is rotten. Two apples are randomly selected from the box. Calculate the probability that a) both the apples are rotten. {3 marks) b) both are red and at least one of them is rotten. {3 marks) c} at least one is rotten if both are red. {4 marks)