Answer:
d) 1/5
Explanation:
If we call x the amount of take-home pay each month and we call y the amount of savings for each month:
The total amount of money she saved at the end of the year (after 12 months) is: 12y
The monthly take-home pay that she didn't save is: x - y
The problem tells us that 12y is three times the amount she didn't save, therefore:
12y = 3(x-y)

Therefore, she saved 1/5 of her take-home pay each month.