Plz help will mark as brainliest

Given this information, which expression must represent the value of b?

Combined megan and kelly worked 60 hours.kelly worked twice as many hours as megan.how many hours did they each worked?

Asimple random sample of size nequals14 is drawn from a population that is normally distributed. the sample mean is found to be x overbar equals 70 and the sample standard deviation is found to be sequals13. construct a 90% confidence interval about the population mean