I think the question is wrong. We need some value to find out the fraction. What is the source of the question?

The actual problem should read something like this:

alice's take home pay is the same each month. she saves same fraction each month. the total amt she saved at the end of the year was 3 times the amt of the portion she did NOT save. if all the money she saved last yr was from her pay, what fraction of her pay did she save each month?

The amount Alice makes each month is x.

The amount that Alice makes in a year is 12*x or 12x.

Let's say Alice saves y dollars from those x dollars that she receives each month.

She doesn't save x-y dollars.

The amount of money that Alice saves in a year is 12*y or 12y

The amount that Alice doesn't save in a year is 12(x-y)

12y=3(x-y)

We're looking for y/x.

12y=3x-3y

15y=3x

1/5=y/x

dude according to the modified question u have put have ,isnt this worng ...

12y=3(x-y)
rhs u have monthly expenditure and lhs you have a yearly savings.. and this hasnt been anywhere apecified in question ..the only thing what question says is total amt she saved at the end of the year was 3 times the amt of the portion she did NOT saveso it should b
12y = 12.3(x-y)

dude according to the modified question u have put have ,isnt this worng ...

12y=3(x-y)
rhs u have monthly expenditure and lhs you have a yearly savings.. and this hasnt been anywhere apecified in question ..the only thing what question says is total amt she saved at the end of the year was 3 times the amt of the portion she did NOT saveso it should b
12y = 12.3(x-y)

The wording is rather ambiguous but when I took a look at other posts that were similar to this one, people had done 12y=3(x-y). This problem was just re-written by someone, and that person had probably written it incorrectly.