Final answer:
Mark worked 23 hours last week.
Step-by-step explanation:
To find the number of hours Mark worked last week, we can divide the amount he earned by his hourly wage.
Mark earned $126.50 and his hourly wage is $5.50, so the number of hours he worked can be calculated as:
Hours worked = Earnings / Hourly wage
Substituting the given values:
Hours worked = $126.50 / $5.50 = 23 hours
Therefore, Mark worked 23 hours last week. Mark's earnings can be found by multiplying the hourly rate by the number of hours worked, which is a fundamental concept in solving problems involving wages and working hours.