Helen plans on reading 2 books this year. If there are 7 books on her reading list to choose from, how many different book choice combinations are possible?
Provide your answer below:

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?

The probability that an adult possesses a credit card is .70. a researcher selects two adults at random. by assuming the independence, the probability that the first adult possesses a credit card and the second adult does not possess a credit card is:

The number of calories you burn depends on your weight. a 110-pound person burns 163 calories during 30 minutes of tennis. find the number of calories that a 190-pound person would burn during the same activity, assuming they burn calories at the same rate.