can you help me solve?

Example 2.2 Traffic engineers have coordinated the timing of two traffic lights to encourage a run of green lights. In particular, the timing was designed so that with probability 0.8 a driver will find the second light to have the same color as the first. Assuming the first light is equally likely to be red or green, what is the probability P{G2] that the second light is green? Also, what is P{W], the probability that you wait for at least one of the first two lights? Lastly, what is P|G';|R2], the conditional probability of a green first light given a red second light