3. If a system of linear equations has zero solutions, then the graph of the system is:
a. intersecting lines b. perpendicular lines c. the same line d . parallel lines.
4. If the result, when solving a system by either elimination or substitution, is 3 = 3, the solution is:
a. (-5, 3)
b. no solutions c. (3,-5)
d. infinitely many

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?