Portia grant is an employee who is paid monthly. for the month of january of the current year, she earned a total of $8,260. the fica tax for social security is 6.2% of the first $118,500 of employee earnings each calendar year and the fica tax rate for medicare is 1.45% of all earnings. the futa tax rate of .6% and the suta tax rate of 5.4% are applied to the first $7,000 of an employee’s pay. the amount of federal income tax withheld from her earnings was $1,325.17. her net pay for the month is:

Atennis club charges a monthly membership fee of $150 and charges it members $10 per hour to use a court. there's also $500 fee to become a member. stella joined the tennis club last spring, and she has been a member for 5 months. she has been playing 10 hours of tennis each month. stella values an hour of her time at $20. during a boring afternoon meeting, stella thinks about reserving a court to work on her serve for an hour tonight. what's stella's opportunity cost of working on her serve for an hour?