Answer: 12 weeks
Step-by-step explanation:
If Keith wants tgo have at least 200 in his account at the end of summer you need to minus it from the original 500 to make a new total.
Now you will have $300 to work with.
Since Keith needs $25 a week you will divide your new total ($300) by 25 and it will give you the number of weeks he can sustain this budget.
300/25=12