Mitch lives on the 20th floor of an apartment building. Every time he leaves, he rides a self-service elevator from the 20th floor to the street; but every time he returns, he rides the same self-service elevator only to the 15th floor, where he leaves the elevator and walks up the remaining five flights of stairs. What is happening? Why does he do that?

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?