Proportional reasoning involves the ability to compare and produce equal ratios. A common use of proportions occurs when making or using maps and scale models.
There are several ways to solve a proportion. One is related to how you find equivalent fractions. To find equivalent fractions, you multiply or divide the numerator and denominator by the same number. Thus, to solve , note that the numerator (2) was multiplied by 3 in order to get 6. Then do the same to the denominator (3) to get n=9. This works well when the numerator and denominator of one fraction are multiples of the other fraction, but it is more difficult to do when they are not, as in the case of . In this case we multiply both sides of the equation by 8n as shown below:
|(multiplying both sides by 8n)|
|(divide out the common factors)|
|(divide both sides by 6)|