The answer is:
9
Half the number before and then add to the next eg ( half 4 = 2 + 4 =6,half 6 = 3+6 =9,half 9=4.5 + 9 =13.5 and so on ....)
12/18 is a equivalent fraction for 6/9. 4/12 is a equivalent fraction for 2/6
One and a half quarts is equivalent to 6 cups.
No, it is not.
360/540 is equivalent.
6/9 is 2/3
Yes, the duration of 6-9 months is equivalent to 9 months in terms of time.
6
It is 9+6 = 15
9 and a half inches
1 half