Final answer:
The server makes $12.50 per hour in tips. Thus, to earn $225, the server would need to work for 18 hours.
Step-by-step explanation:
To calculate how many hours the server would have to work to earn $225 in tips, we first establish the server's hourly tip rate. Since they make $50 in tips for a 4-hour shift, we divide $50 by 4 to find the rate per hour:
$50 ÷ 4 = $12.50 per hour
Next, to find out how many hours are needed to reach $225 in tips, we divide $225 by the hourly tip rate:
$225 ÷ $12.50 = 18 hours
Therefore, the server would need to work 18 hours to earn $225 in tips.