398

Glass.

Pencil.

Time.

Sleep.

1, 2 and 3
1 + 2 + 3 = 1 x 2 x 3 = 6

Fire.

Bubblegum

Sand

98¹ - 2 = 96

Flip it upside down!

16 = 8 + 8.

18 years.
You were 9 and Your sister was 1/3 of your age i.e her age was 3 years.

It means the difference between your ages was 9–3 = 6.

So now, when your sister is 12 years old then you must be 12+6 = 18 years old.
Again if you check the difference between your age and your sister's age that is 18–12 = 6.

So Your Age in this way is 18 Now.