3 10 and 9 20 do not form a proportion because 3 10 does not equal 9 20 Explanation: A proportion, by definition, means that two ratios are equal. To check if two ratios are equal, you have to bring both to their simplest form and see if you get the same value. Let's look at the two ratios we have and see if we can simplify them. 3 10 cannot be simplified any further because 3 and 10 do not have any common factors. 9 20 also cannot be simplified any further for the same reason - this means that the two ratios we had are already in simplest form. Therefore, 3 10 and 9 20 do not form a proportion because 3 10 does not =
9 20 3 10 and 6 20 would have formed a proportion though because we can simplify 6 20 by dividing the numerator and denominator by the common factor of 2 to get 3 10 .
