Remark
Deposit means put money in (think of your mom and the bingo winnings from the last problem).
Withdraw means take money out (think of it as buying the video game).
So you are adding and subtracting again.
So you start with a deposit of 300 dollars. (Money in). That is a plus number.
Your next step is to withdraw money. So that step looks like 300 - 50 = 250
Your third step is to withdraw more money. It's another take away 250 - 75 = 175.
Your last step is a deposit which means you are using a positive number.
175 + 225 = 400.
When you do questions involving bank accounts repeat this lyric.
Deposit is a plus number. Withdraw is a minus number. They are never anything else.
Problem B
The sum is 400. It means that even with all the spending, your bank account has gone up. You can't tell by how much because you don't know what was in there before.
