18 ÷ 6 = 3
6 ÷ 6 = 1
Therefore, one equivalent ratio is 3/1
In order to find any other equivalent ratios, all you need to do is multiply/ divide the same number by both the numerator and the denominator.
Two more examples:
3 X 3 = 9
1 X 3 = 3
9/3
3 X 10 = 30
1 X 10 = 10
30/10