If 3/4 of a class is absent and 2/3 of those present leave the room, what fraction of the original class remains in the room?

my book says..
if 3/4 are absent, 1/4 are present
hows that so?
then it says if 2/3 of the 1/4 present , 1/3 of the 1/4 remain leave 1/3x1/4 =1/12 I don't understand? Do I add or?? Im not sure please help me

I think you'll find it easier if you introduce a variable for the number of students in the room. Suppose there are N students.

If a fraction of 3/4 is absent, then that means that the number of absent students is 3/4 N. Now the total number of students is N, so the difference
N - 3/4 N is the number of students that are present.

N - 3/4 N = (1-3/4) N = 1/4 N

So, a fraction 1/4 of the number of students are present.

ok so its 1-3/4? can you subtract that for me im not sure how to

Imagine a pizza that's cut into four equal parts. If your friends eat three pieces, they've eaten 3/4 of the pizza. That leaves 1/4 of the pizza for you.

Showing it mathematically:

1 - 3/4 =
4/4 - 3/4 = 1/4

Another way of looking at 1 - 3/4 is to think of money.

A dollar has 4 quarters (4/4). If you spend 3 quarters (3/4), you have one quarter (1/4) left.

The second part of your question states 1/3 of the 1/4 remain leave. Remember that the word "of" indicates you need to multiply. So ...

1/3 x 1/4 = ??

If you have trouble remembering how to multiply fractions, check one of these sites:





Or does it state that 2/3 of the 1/4 present leave? If so, then the multiplication problem is 2/3 x 1/4 = ??

I wish they would of left me 2/4 of the pizza. Thank You very Much! that explains it!

You're welcome! I'm glad I could help explain it to you. Just remember, fractions can sometimes be a bit tricky, but with a little practice, they'll become as easy as pie... or pizza! If you have any more questions, feel free to ask.

You're welcome! I'm glad I could help clarify it for you. If you have any more questions, feel free to ask!

You're welcome! I'm glad I could help explain it to you. Remember, when you see the word "of" in a fraction problem, it usually means multiplication. And when you see fractions being subtracted, you can think of it as taking away parts from a whole. Good luck with your math!