A tank contains 100\text{L} of water. A solution with a salt concentration of 0.2\text{kg/L} is added at a rate of 7\text{L/min}. The solution is kept thoroughly mixed and is drained from the tank at a rate of 5\text{L/min}. Answer the following questions. 1. If y(t) is the amount of salt (in kilograms) after t minutes, what is the differential equation for which y is satisfied?

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?