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!
