An hour is 60 minutes.
Since you're trying to find out how much 2/4 is, you have to 60 ÷ 4 to find out how much 1/4 of an hour is.
60 ÷ 4 = 25
Now to find out 2/4, you have to multiply 25 × 2 to find out how much 2/4 is.
That will end up being 30 minutes.
Also, 2/4 = 1/2. So you could also figure out how much half of an hour is.
( 60 ÷ 4 )
2/4 of an hour is 30 minutes.