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Dividing whole numbers & fractions: t-shirts

Video transcript
A baby's T-shirt requires 4/5 yards of fabric, or 4/5 of a yard of fabric. How many T-shirts can be made from 48 yards? So what we want to do is we essentially want to say how many groups of 4/5 of a yard can we make with 48 yards? So you literally view this as we want to take 48 yards and divide it into groups of 4/5 of a yard, and say how many groups are there? Because each of those groups can make one to baby's T-shirt. If you give me 4/5 of a yard, one baby's T-shirt, so the number of groups of 4/5 is the number of babies' T-shirts. Now, when we divide by a fraction, we just have to remember that that is the same thing, that is completely equivalent to multiplying times the reciprocal of the fraction. So if we have 4/5 here, that'll be 5/4, the reciprocal. Now, you still might say, hey, I have a whole number here and a fraction, and you just have to remember any whole number can be written as a fraction. This is the same thing as 48/1 times 5/4. Now, we could just multiply it out at this point and figure out what 48 times 5 is and that'll be over 4, but that'll get big numbers and it'll be hard to kind of divide and all that, but we could divide at this stage right here. We could divide the numerator and the denominator by 4. Or we could say, look, this is going to be equal to 48 times 5, whatever that is, over 4. Now, let's divide the numerator by 4. Well, we could divide 48 by 4, and we will get to 12, and whatever we did to the numerator, we have to do to the denominator, so if we divide 4 by 4, we get 1. So then we're left with 12 times 5, which is equal to 60. 12 times 5, which is equal to 60/1, which is the exact same thing as 60. So you can actually make 60 children's or babies' T-shirts from 48 yards if each of them use 4/5 of a yard.