$3\mathrm{.}4-15.$ Joyce and Marvin run a day care for preschoolers. They are trying to decide what to feed the children for lunches. They would like to keep their costs down, but also need to meet the nutritional requirements of the children. They have already decided to go with pcanut butter and jelly sandwiches, and some combination of graham crackers, milk, and orange juice. The

$87$

minimum amount of income needed for each of the future time periods when a new hydroelectric plant will be constructed.