Let s = fa; b; c; d; e; f; gg be a collection of objects with benefit-weight values as follows: a: (12; 4); b: (10; 6); c: (8; 5); d: (11; 7); e: (14; 3); f : (7; 1); g: (9; 6). what is an optimal solution to the fractional knapsack problem for s assuming we have a sack that can hold objects with total weight 18? show your work.