What you need to do is find the smallest multiple that they both have (i forgot what that is called) list them like this:
12: 24 36 48 60 72
15: 30 45 60 75
60 is the lowest number that they both can multiply to
60 cups/lids is the answer
Y= my+b
-2=0/3x -2
I’m actually not very sure about this but
last one. because we don't have equality sign and it can't be the third one
1/3 : 2/6
1/2 : 2/4
15/31 : 45/93
hope this helps (;