rational numbers can be written as a ratio of two integers a/b
1/2 is the ratio of 1 and 2 so its rational
√7/10 is not a ratio of two integers so its irrational
3π/4 is not a ratio of two integers so its irrational
5/9 is the ratio of 5 and 9 so its rational
18 is 18/1 and is the ratio of 18 and 1 so its rational
