Virtual Nerd: How Do You Subtract Fractions With the Same Denominator?

Having a common denominator is the best thing to have when subtracting fractions. If you have a common denominator then all you have to do is subtract the numbers in the numerator.

Having a common denominator is the best thing to have when subtracting fractions. If you have a common denominator then all you have to do is subtract the numbers in the numerator.

Watch how to subtract fractions with different denominators by finding a common denominator. [3:27]

Want to add fractions? Well, if they have the same denominator it's going to be so easy. Just add the numerator values together and keep the denominator the same. Easy as that.

Combining fractions with unlike denominators. Wait! You can't do that! You have to have common denominators to combine the numerator of fractions. Here's a quick review of changing the denominator by multiplying each fraction by that...

Combine fractions that have unlike denominators and a variable. As usual the variable needs to get isolated. Then find the least common denominator so you can combine the fractions. Finally put it all back together.

Probability is the likelihood that a given event will take place. So how do you determine the probability of a simple event? Watch this example using marbles for an explanation. [4:36]

You've got three fractions to add together. Wait! They have unlike denominators. So the first thing you have to do is find the least common denominator. Now multiply the terms so they all have the same denominator. Don't forget to...

Combining terms that have fraction coefficients means you have to use your prior knowledge of adding and subtracting fractions. Find the least common denominator so you can combine the fractions. Finally put it all back together.

Combine fractions that have unlike denominators and a variable. As usual the variable needs to get isolated. Then find the least common denominator so you can combine the fractions. Finally put it all back together.