Please help with 7,8 and 9!

Contribution margin ratio is equal to. fixed costs divided by contribution margin per unit. net sales revenue per unit minus variable costs per unit net sales revenue minus variable costs contribution margin divided by net sales revenue The Button-Down Custom Co. sells hand-sells hand-sewn shirts for $40 per shirt. It incurs monthly fixed costs of $7,000. The contribution margin ratio is calculated to be 30%. What is the variable cost per shirt? $28.00 per shirt $52.00 per shirt $40 per shirt $70.00 per shirt Lori sells hand-knit scarves at a flea market. Each scarf sells for $35. Lori pays $70 to rent a vending space for one day. The variable costs are $20 per scarf. How many scarves she sell each day in order to break even? 35 scarves 5 scarves 7 scarves 4 scarves