Alice's take home pay was the same each month last year, and she saved the same fraction of her take home pay each month. The total amount that she had saved at the end of the year was 3 times the amount of that portion of her monthly take home pay that she did not save. If all the money she saved last year was from her take home pay, what fraction of her take home pay did she save each month.
1. 1/2
2. 1/3
3. 1/4
4. 1/5
5. 1/6
Please help me answer this question, with the explanation.