KöMaL 2016 K512

Patrick, Peter and Paul are triplets. One day, they were walking with their mom, and they saw a chewing gum vending machine. It contained a mixture of gums of three different colours (red, yellow and green). 100 forints (HUF, Hungarian currency) need to be inserted in the machine to get a chewing gum. The triplets insisted on getting gums of the same colour. Their mom kept throwing coins in the machine until she was able to fulfil the children's wish. They walked the same route on four consecutive days, and bought chewing gum in the same way every day. What is the maximum amount of money the mom may have spent on chewing gum, if she did all she could to economize?