The cost structure of Dennis's Retail Mart is dominated by variable costs with a contribution margin ratio of $0\mathrm{.}32$ and fixed costs of $$62,000.$ Every dollar of sales contributes $32$ cents toward fixed costs and profit. The cost structure of a competitor, Oakfield Convenience Store, is dominated by fixed costs with a higher contribution margin ratio of $0\mathrm{.}68$ and fixed costs of $$582,800.$ Every dollar of sales contributes $68$ cents toward fixed costs and profit. Both companies have sales of $$1,240,000$ for the year.

Required:

a$.$ Compare the two companies' cost structures.

b$.$ Suppose that both companies experience a $20$ percent increase in sales volume. By how much would each company's profits increase?