Please have working out for each blank spot. I am confused on how to calculate total fixed costs.

PROBLEM M2.7 Contribution Margin: Unit Amounts information on four independent companies is given below. Calculate the corred amount for each question mark. A B C D Sales $5,000 3 ? $9,000 Total variable cost M} 1 1,700] 1%) 3 Contribution margin $1,000 $3,900 3 3 Total xed cost _a [4,000] _3 ) Net prot $ 500 s e m M Units sold 3 1,300 i 25 90 Price/unit $5 3 $130 3 Variable cost] unit '9' $9 8 3 Contribution margin/unit ? $3 ? 3 Contribution margin ratio 3 9 60% 3 Break-even in units 6 $ $ 3