Proportions are 2 ratios that are equal.
Checking for proportions is quite simple. All you need to do is cross multiply and if both are equal, then it is a proportion, but if it not, then it isn't a proportion. For example, let's say that we are told to check if the two ratios, 16/24 and 4/6, are a proportion. To do so, we cross multiply. We multiply 16 • 6, which equals 96 and 24 • 4, which also equals 96. The two are equal, which means that yes, it is a proportion. In another example, we are told to do the same thing but with 30/63 and 5/9. Again, we cross multiply. 30 • 9 equals 270 and 63 • 5 equals 315. Are the two equal? No. This means that they aren't a proportion.