Question

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

Answer 1

Answer:

The value of x is 12.5.

Step-by-step explanation:

We are given with the following proportion below;

 $\dfrac{12}{30}=\dfrac{5}{x}$  

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,  $\dfrac{\frac{12}{2.4} }{\frac{30}{2.4} } = \dfrac{5}{x}$  

This means that $x=\frac{30}{2.4}$

                           $x=\frac{300}{24} = 12.5$.

So, we get the value of x = 12.5.

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

$\dfrac{12}{30}=\dfrac{5}{12.5}$

$12 \times 12.5 = 5 \times 30$

150  =  150

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

Answer 2

Answer:

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.