probability question

A hag contains 3 green halls1 4 red halls? and no other hails. Victor removes hails randome from the bag, one at a time, and places them on a table. Each ball in the bag is equallyr lilrael},r to be chosen each time that he removes a hall. He stops removing hails when there are tum halls of the same colour on the table. What is the probability that1 when he stops, there is at least 1 red hall and at least 1 green hall on the table