Final answer:
Darnell earned a total of $100 by walking a neighbor's dog for 10 weeks at a rate of $10 per week.
Step-by-step explanation:
Darnell earned $10 each week for 10 weeks, walking a neighbor's dog. To find out how much he earned in total, we multiply the amount earned per week ($10) by the number of weeks (10). So, the total amount Darnell earned is $10 x 10 = $100.