(-3*10^9)(1.27*10^-12) in scientific notation

Solve - pv + 40 < 65 for v solve 7w - 3r = 15 for r

You have 17 cats that live in houses on your street, 24 dogs, 3 fish, and 4 hamsters. what percent of animals on your block are dogs?

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.