Final answer:
Joe will have saved $375 after 20 weeks.
Step-by-step explanation:
To find out how much Joe will have saved after 20 weeks, we can use the formula:
Total Savings = Initial Savings + (Weekly Savings x Number of Weeks)
Joe begins with $75 and saves $15 per week for 20 weeks:
Total Savings = $75 + ($15 x 20) = $375
Therefore, Joe will have saved $375 after 20 weeks.