How do i solve this problem?

The probability you're asked to find is



where is the event that either event occurs (A, B, or both), and is the event that both events occur.

Recall that



which means



You're told that , , and (if I'm reading the diagram correctly) .

So,



Another way of seeing this is that the event A consists of the regions "A not B" and "A and B". So the probability that "A not B" occurs is



Similarly, B consists of "B not A" and "A and B", so you have



So the probability that A or B, but not both, occur is

Iwould say false, not positive but if prices went up for both stores, technically there will be less buyers?