Jim Ross is an automobile salesman who receives a salary of $500 per week plus a commission of 3% on all sales. During a four-week period he sold $42,000 worth of cars. What were Jim's average earnings?

4 * 500 = $2,000

Then, you must calculate how much he earned by the commission:

$42,000 * 3%

(3% = 3/100)

42,000 * 3/100 = 420 * 3 = $1260

Finally, you add what he earned form the commission plus the 4 weeks salary:

$2,000 + $1260 = $3,260