In a survey of 600 people, it was found that 255 drink fruit juice, 260 drink colas, 250 drink wine, 90 both drink colas and wine, 110 drink fruit juice and colas, 80 drink both fruit juice and wine, 30 drink all three beverages.
a. Find the number of people who drink at least one of the two beverages.
b. Find the number of people who drink exactly two beverages.