Answer:
The answer is 4 months
Step-by-step explanation:
We consider the months is 4 weeks and the service fee will be discounted every 4 week.
Spent of each months will be ( 25*4)+5
S=105
To see how many months will last, we divide all the money we have by the amount we are going yo spend.
T=420/105=4
We also can make a table, discounting every week the amount of withdraw and service.
Withdraw/Bank cost/ Balance
$420
Week 1 $25 $5 $390
Week 2 $25 $365
Week 3 $25 $340
Week 4 $25 $315
Week 5 $25 $5 $285
Week 6 $25 $260
Week 7 $25 $235
Week 8 $25 $210
Week 9 $25 $5 $180
Week 10 $25 $155
Week 11 $25 $130
Week 12 $25 $105
Week 13 $25 $5 $75
Week 14 $25 $50
Week 15 $25 $25
Week 16 $25 $0
