Question

How could you use cross products to check the solution to this proportion?

12

30

=

5

x


30(5) = (12)(x)


150 = 12x


12.5 = x

Answer 1

Substitute 12.5 for x in the original proportions: 12/30 = 5/12.5. Then cross multiply and verify that the two products are equal: 150 - 150.

Answer 2

The value of x is 12.5.

Explanation:

We are given with the following proportion below;

`(12)/(30)=(5)/(x)`

To find the value of
`x`, first we have to find the number by which 12 must be divided so that we get 5 as a result.

That number is 2.4, that is if we divide 12 with 2.4 we get the result as 5.

So,
`((12)/(2.4) )/((30)/(2.4) ) = (5)/(x)`

This means that
`x=(30)/(2.4)`

`x=(300)/(24) = 12.5`.

So, we get the value of x = 12.5.

Now, to check the solution to this proportion, we use cross multiplication method;

`(12)/(30)=(5)/(12.5)`

`12 * 12.5 = 5 * 30`

150 = 150

Since both sides of the equation are equal, that means our value of x = 12.5 is correct.