Ruby is moving from Minneapolis to Chicago, which is 400 miles away. She is traveling at an average speed of 50 miles per hour. Ruby stops for gas after a couple of hours and wonders how much further she needs to go. If y represents distance and x represents time, which linear equation would indicate the amount of miles Ruby still has to travel to Chicago?

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?