We have to find the intersection of the probability of A and B, so we have to look at their sets.
A: {2,4,6,8,10} - All of the even numbers in the set of 1-10.
B: {7,8,9,10} - All of the numbers 7 or above in the set of 1-10.
As you can see, 8 and 10 are in both sets. There are only 2 numbers that intersect, so the intersection is 2/10. Since the answer has to be expressed as a decimal, then the final intersection of probability A and B would be 0.2.