Helen rented a kayak at the lake. there is a charge of $8 as an initial fee and then $2 an hour for every hour that she uses the kayak. if the total charge is $20, how many hours did she kayak?

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.