if you save 4 for the first week, 8 dollars 2nd week, 12 dollars 3rd week and so on how much will you have after 60 weeks
You will have:
=$7,320
$7320 is correct if you add $4 every week,
but if you meant you add your first $4 to $8 (=12), then add that to the third week $12 (=24),
then $7320 would be how much you save in week 60 alone, and the total would be $151,280