How can you tell if the content on a website is modified regularly?

Which of the following are sources of revenue for media companies? a. direct sales to producers b. advertising and subscriptions c. online purchase d. capital investments

Find the mass, in grams, of 5.00*10^23 molecules of f2

Sum of brother and sisters age is 26. four times the brothers age is subtracted from three times the sisters age, the difference is 8. what are the ages of the brother and sister?