Final answer:
Brad's earnings for the night are calculated by adding his hourly wage for 6 hours to his tips, which are 18% of the $840 bills he served. The total earnings are $166.20, which shows a discrepancy with the provided options in the question.
Step-by-step explanation:
Brad's earnings for the night can be calculated by determining his hourly wage earnings plus the tips he received. Brad worked for 6 hours at $2.50/hr, which amounts to $15.00. The total bill for his tables was $840, and he received an average of 18% in tips on this amount. The calculation for tips would be 18% of $840, which is $151.20. Adding his hourly wage earnings and tips gives us his total earnings for the night ($15.00 + $151.20 = $166.20).
However, since this amount is not included in the provided options, it seems that there was a misunderstanding in the calculation or the options provided in the question were incorrect. Double-checking the calculation: $2.50/hr × 6 hours = $15.00 from the hourly wage. And for tips: 0.18 × $840 = $151.20 from the tips. So, Brad's total earnings for the night should indeed be $15.00 + $151.20 = $166.20.