I'm basically seeing if I take one of the numbers out then cross multiply, and see if I get the same number I took out or not.  
6. I'm taking the 2 out for this one.
6*8=48 
48/ 24=2 
it should be proportional. 
7.I'm taking out the 2 
5*8= 40
40/25= 1.6
this one should not be proportional