To calculate the net benefit of playing the round of golf, we need to determine the cost of playing the round of golf and the value of the benefits we receive from playing it.
Cost of playing the round of golf: $31
Value of playing the round of golf: $85
Opportunity cost (value of time if not playing golf): $19/hour
Time to play the round of golf: 2 hours
Therefore, the opportunity cost of playing golf is:
Opportunity cost = Value of time × Time spent
Opportunity cost = $19/hour × 2 hours
Opportunity cost = $38
The net benefit of playing golf is the value of the benefits minus the cost and the opportunity cost:
Net benefit = Value of benefits - Cost - Opportunity cost
Net benefit = $85 - $31 - $38
Net benefit = $16
Therefore, the net benefit of playing the round of golf is $16.