I changed the numbers in your problem:
Uzma is 16 year old. Asma is one-fourth older then Uzma.
How many years ago has it been since Asma was three times as old
as Uzma?
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Uzma is 16 year old.
U = 16
Asma is one-fourth older then Uzma.
A = U + U
Substitute U=16
A = 16 + (16)
A = 16 + 4
A = 20
How many years ago has it been since Asma was three times as old
as Uzma?
Let number of years ago = y
Azma was A-y and Uzma was U-y
A - y = 3(U-y)
Substitute A=20, U=16
20 - y = 3(16-y)
20 - y = 48 - 3y
2y = 28
y = 14
Checking: 14 years ago Uzma was 2 and Azma was 6.
6 is three times 2.
Now you can do your problem.
Edwin