4) (You do not need to write the mathematical formulation for this problem.) Alex and Isabela have a daughter who is 13 years old this year, and their daughter, Emma, will be starting college 5 years from now. According to Isabela's estimation, Emma will need $12,000 in her first college year and the yearly tuition increases $2,000 per year during each of the remaining three years of her education. The following investments are available to the Alex and Isabela: < Available Investment A B C D Every year 1, 3, 5, 7 1,4 14 Matures 1 year 2 year 3 year 7 year Return a. Draw a diagram depicting this problem as a network flow problem. < b. Solve using Excel Solver. < 6% 14% 18% 65% Alex and Isabela want to find an investment plan that will provide the necessary funds to cover Lisa's anticipated college expenses with the smallest initial investment. < 2 2 J