Karen deposited $25 in the bank on Monday, $50 on Wednesday and $15 on Friday. On Saturday, she took out $40. Karen's original balance was $100. What is her balance now?

In order to solve this problem, use sign conventions. Since deposit indicates cash inflow, that would take the positive sign. On the other hand, withdrawals take negative sign. We add these integers to the original balance. he solution is as follows:

$100 + $25 + $50 + $15 + (⁻$40) = $150