You can multiply both sides by 2 so you get 8\18. 8\18 is equivalent to 4\9. You can also multiply 4\9 by any other natural number as long you multiply both numbers of the fraction by the same natural number.
you multiply both side for the same number,
4/9 * 2 = 8/18
4/9 * 3 = 12/27
4/9 * 4 = 16/36
