1) [50 points] Sally and Joe are stuck on a desert island. The only two activities available to them is playing checkers and making ice cream. Sally's and Joe's time in ice cream production are perfect substitutes: I=f(2tSi+tJi) where I is the amount of ice cream produced, tSi is the amount of time Sally spends making ice cream, and tJi is the amount of time Joe spends making ice cream. Note that Sally is twice as productive as Joe in making ice cream. Sally's and Joe's time in playing checkers are perfect complements: C=g(min[tSc,tJc]) where C is the amount of checker playing produced, tSc is the amount of time Sally spends playing checkers, and tJc is the amount of time Joe spends playing checkers. Assume that the joint utility function of Joe and Sally is U(C,I) and that Joe and Sally each have only 1 unit of time available: tSi+tSc1tJi+tJc1 How do Joe and Sally each split their time between checkers and ice cream making?.