Solving Proportions

Presented by: Isabelle Howrey

Let's talk about proportions

First things first

You should already have a proportion lined up and ready to solve. First things first, you need to take the denominator of the first fraction and multiply it by the numerator of the second fraction. If you have a variable in one of your fractions, it works just the same as if you had a number.

Second step...

As you can see in the picture above, they went ahead and did the second step. The first step is in red and the second step is in blue. All they did in the second step was take the numerator in the first fraction and multiply it by the denominator in the second fraction.

Time to solve!

Next, your numbers/variable should look like the equation in the picture. Now, you need to take the number right next to the variable and divide the number by itself, to cancel it out. Once you have the variable all by itself, you do the exact same thing on the other side of the equal sign. As you can see in the picture above, they haven't quite finished solving the proportion.

let's do a practice problem!


let's solve!

So, first we need to cross multiply 3 and 27. Next, we need to multiply x and 9. 27 times 3 is 81 so instead of having 3/9, you will have 81. Instead of having x/27, you should have 9x. Now you need to cancel out the 9 to get the x by itself by doing 9 divided by 9. So, your equation should look like this before you do 9 divided by 9: 81=9x.

now it's your turn!

I need some help solving...could you help?

What was the first step you took?

Then what did you do?

Now what?

Anything else?

Are we done?

a. 1.8

Remember, you can always practice at home if you don't quite understand!!

Hope you enjoyed learning how to solve proportions!

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