Verified Answer :

2:6

3:9

4:12

These are all equivilant

1:3

Multiply by 2, 3, 4, 5.

21: 23 =  2 : 6

31: 33 =  3 : 9

41: 43 =  4 : 12

51: 53 =  5 : 15

Equivalent ratio could be either of  2:6,  3:9, 4:12, 5:15

Hope this helps.