I'll give you a question, please answer with step-by-step reasoning process.
Last month, you borrowed $100 from your friend. If you promise to pay her today, how much will you give to your friend if both of you agreed to return the money with a 10% increase?

110
The increase is $100 x 10 / 100 = $10.

So you have to give $100 + $10 = $110 to your friend today.

.

Thus, the answer is 110