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Adding and subtracting fractions

Adding and subtracting fractions

From the course: Test Prep: GRE

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Adding and subtracting fractions

- [Voiceover] This video I'll talk about fractions just in terms of adding and subtracting them, and also I'll go into how to reduce and expand the fraction a little bit. So let's just talk about adding fractions. The easiest way to add fractions is if you have two fractions that have the same denominator. So let's say I had one fourth plus two fourths. That's easy; I just go straight across, one plus two is three, and then I keep the denominator the same. Easy, and the same thing happens with subtracting fractions. Let's say I had five sixths minus two sixths, well, that would be three sixths. Again, we would just go straight across in the numerator, five minus two is three, keep the denominator the same. But what if I had a situation like this? What if I had one third plus one half? Well, that's a problem for a minute here. We can't just add these two unless they have a common denominator like we did over here. So what we do is we give them a common denominator. The easy way to do…

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