Let's say Liyana has 4 units at first.

Giving ¼ of her stickers means 1 unit is given to Sim Yee.

(4 units x ¼ = 1 unit or 4 units ÷ 4 = 1 unit)

So Liyana has 3 units left.

Since Liyana would have ¼ of Sim Yee's stickers after that,

The ratio is 1 : 4. Change the ratio to make Liyana's units to 3.

Multiply by 3,

1 : 4 = 3 : 12

So Sim Yee has 12 units now.

12 units - 1 unit = 11 units

Sim Yee has 11 units at first.

So at first,
Ratio of Liyana's stickers to Sim Yee's stickers = 4 : 11

Thank u v much. I understnd ur way better.

Welcome. My method is actually the same as AC's. Just that he included the concept of total unchanged.