Mark and his workout partner are lifting weights together, doing many sets of each exercise. On a certain exercise, Mark is using a 40-pound bar, increasing the amount of weight he lifts by 5 pounds on each set. His partner, meanwhile, started out using a 20-pound bar and is upping the weight by adding 10 pounds on every set. Eventually, Mark and his workout partner will be lifting the same amount, and will take turns using the same barbell. How much weight will they be lifting then?

Data from 2005 for various age groups show that for each $100 increase in the median weekly income for whites, the median weekly income of blacks increases by $105. also, for workers of ages 25 to 54 the median weekly income for whites was $676 and for blacks was $527. (a) let w represent the median weekly income for whites and b the median weekly income for blacks, and write the equation of the line that gives b as a linear function of w. b = (b) when the median weekly income for whites is $760, what does the equation in (a) predict for the median weekly income for blacks?