So it's 0.8 to the fourth power times 0.2 squared. And it doesn't matter. Any of the unique combinations will each have the same probability, because we can just rearrange the order in which we multiply. And then how many of these combinations are there? If we are, once again, the god of probability, and out of 6 flips, we are choosing 4 that are going to end up heads. How many ways can I pick a group of 4? Well, once again, that's times 6 choose 4.