Let’s assume his hourly rate is $12.20, so in a 40-hour week he would earn 40×12.20=$488.
But he missed some hours through sickness (unpaid). So he was deducted for the hours he wasn’t at work.
By simple proportion h/40=372.10/488, where h is the number of hours he worked. The proportion of pay is the same as the proportion of hours. Therefore h=40×372.10/488=61/2=30.5 hours.