Proportions – If two ratios are equal, then they are said to be in proportion. Symbol or is used to equate the two ratios.
Example: Ratios 2:3 and 6:9 is proportional.
The Lowest form of the Ratio – If except one there is no common factor of numerator and denominator then it is the lowest form of the ratio.
Example – Find lowest form of the ratio 10: 100.
Solution: The common factor of 10 and 100 is 10, so divide both the numerator and denominator with 10. Hence the lowest ratio of 10: 100 is 1: 10