you've got a summer job renting beach umbrellas and chairs to tourists at the beach. part of your job is to encourage people to rent from you, your pay structure includes an incentive. along with a daily rate of pay of $50, you earn an extra $2 per umbrella you rent and $1 per chair you rent. you kept a tally of the number of umbrellas and chairs you rent each day. what is the function you can use to quickly calculate your earnings?