15.23 Review of straight lines. Fred keeps his savings in his mattress. He began with $1000 from his mother and adds $250 each year. His total savings after years are given by the equation
(a) Draw a graph of this equation. (Choose two values of , such as 0 and 10. Compute the corresponding values of from the equation. Plot these two points on graph paper and draw the straight line joining them.)
(b) After 20 years, how much will Fred have in his mattress?
(c) If Fred had added $300 instead of $250 each year to his initial $1000, what is the equation that describes his savings after years?