The circumference of a circle B is 80% of the circumference of circle A find the ratio of the area of circle A to the area of circle B. giving your answer in the form 100:n

The salesperson earns a 5% commission on the first $5,000 she has in sales. the salesperson earns a 7.5% commission on the amount of her sales that are greater than $5,000. this month the sales person had $8,000 in sales. what amount of commission, in dollars, did she earn?