To find simple interest, you multiply the principal (in dollars), the interest rate (as a decimal), and the time in years. The equation 24=400*0.015*4 shows how to find the simple interest for a certain account after years. What is the interest rate (as a percent)? How much is the simple interest? What is the principal?

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?