Can someone explain how you get $170!! please

There's a lot of extra information here that isn't necessary. First you have to ask yourself what is the pattern? How much does he deposit each week? If you look you'll see he deposits $14 each week. So if he deposits $14 for 10 weeks that's $140 plus the $30 he started with on the first week=$170.

Hopefully that helps. You have to find what information is pertinent to the question and weed out what is extra information given to throw you off.

2.83941151 would be the answer you're looking for! : )