fill in the missing amounts in each of the eight case situations below. Each case is independent of the others a. assume that more than one product is being sold in each of the following four case situations: case 1 sales 502000 operating income (loss) 7100 average contribution margin (percentage) 20% a. what is the variable expenses b. what is the fixed expenses case2: sales 402000 variable expenses 261300 fixed expenses 100500 a. what is the operating income (loss) b. what is the average contribution margin (percentage) case 3: fixed expenses 130600 operating income (loss) 20600 average contribution margin (percentage) 60% a. what are the sales b. what are the variable expenses case 4: sales 602000 variable expenses 421400 operating income (4800) a. what are the fixed expenses b. what is the average contribution margin (percentage)