For what value of x is line a parallel to line b?

What is the value of r of the geometric series?

How many $20 bills do you need to have to make $280

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.