In this video, we will be learning how to solve proportions using cross-multiplication. After you finish this lesson, view all of our Pre-Algebra lessons and practice problems.
For Example:
First we cross-multiply
Then we divide by 5 to isolate x
Examples of Solving Proportions
Example 1
First, we have to cross-multiply.
then
Next, distribute to
Subtract from both sides
Divide from both sides to get
Our final answer is
Example 2
First, we have to cross-multiply.
then
Next, distribute to
Add from both sides
Divide from both sides to get
Our final answer is
Video-Lesson Transcript
In this video, we will be learning how to solve proportions using cross-multiplication.
Ratio = Ratio
Or
Solving Proportions comes in when there is an unknown.
Let’s say we have
We have to cross-multiply.
then
We have
Then we get the value of
But what about it is not a perfect multiplier?
For example,
In this case, we cross-multiply then
So we have
Here we have to
So
Here’s another example.
Let’s cross-multiply, then
We have to distribute
And we’ll have
To get the value of we have to
Our final answer is