Question

Find the missing number in this proportion.

30/90 = ?/18

Answer 1

1/3 = ?/18

1/3 * 18 = ?

6 = ?

...

Answer 2

Explanation:

We can use the cross-multiplication method to solve this proportion.

Cross-multiplication means we multiply the numerator of one ratio by the denominator of the other ratio, and then set them equal to each other. Like this:

30 × 18 = 90 × ?

Now we can solve for the missing number by dividing both sides by 90:

30 × 18 / 90 = ?

Simplifying the left side, we get:

6 = ?

So the missing number in the proportion is 6. Therefore:

30/90 = 6/18