7. Consider the following cash flow diagram (i = 4%). $2,500 $2,500 $2,500 $2,500 $2,000 $1,500 $1,000 0 1 2 3 3 4 5 6 7 a. Write at least three different expressions for calculating the present worth. (e.g., P = $X(P|A i%, n) + $Y(P|G i%, m) + ...) b. What is the present worth of these cash flows