A farmer decides to move his cows to a nearby farm using helicopters and trucks. A helicopter can take 3 cows per trip and creates 5 units of pollution. A truck can take 7 cows per trip and creates 10 units of pollution. The farmer needs to transport 80 cows and he only has enough money for at most 8 truck trips. How many of each type of trip should be taken to minimize the total amount of pollution produced?