Formulate the mathematical program model for selecting among three projects described below, using maximizing the sum of NPV's of the projects selected as the objective function. MARR = 8 %. There is a budget constraint of $ 13000 at time 0, and the projects are required to generate $ 3500 at t = 1 and $ 1200 at t = 2 (ATTENTION: This is different from the budget constraint as we discussed in class. Think about it what is a reasonable math representation of this?). The life of each project is 5 years. The projects are independent except that C cannot be selected unless A is also selected. No fractional funding is allowed. What is the value of extra budget money at t = 2? Project A B C Investment $ 5000 $ 7000 $ 8500 Annual cash flow $ 1319 $ 1942 $ 2300