Final answer:
The salesman earned $208.89 in commission last week.
Step-by-step explanation:
To find out how much the salesman earned, we can first calculate the total amount he sold the TVs for by using the given information. Since he sold 5 TVs for a total of $18,990, we can divide the total amount by the number of TVs sold: $18,990 / 5 = $3,798. Next, we can calculate the commission he earned by multiplying the total amount by the commission rate: $3,798 x 5.5% = $208.89. Therefore, the salesman earned $208.89 in commission last week.