Which table does not represent a proportional relationship?

Hey there!

First one- 6/4= 3/2(simplified), 21/14= 3/2, 30/20= 3/2 so this is proportional relationship since it's constant

Second one- 5/4 does not simplify to 3/2, 7/6 also doesn't and 9/8 also doesn't, so this is NOT a proportional relationship 

Third one- 9/6= 3/2, 15/10=3/2, 24/16= 3/2. Proportional relationship

Last one- 12/8= 3/2, 18/12=3/2,27/18= 3/2 so this is proportional 

The second one is NOT a proportional relationship

Hope this helps!