You can solve this problem by applying the proccedure below:
You have:
a) 18/21=2/3
18x3/21x2
36≠42 (2/3 is not proportinal to 18/21).
b)18/21=30/35
18x35/21x30
630=630 (30/35 is proportional to 18/21)
c)18/21=36/48
18x48/21x36
864≠756 (36/48<span> is</span><span> not proportinal to 18/21)
</span>
d)18/21=1/3
18x3/21x1
54≠21 (<span> 1/3 is</span><span> not proportinal to 18/21)
</span>
Therefore, you can conclude that the correct option is: B.30/35
I believe that number would be 6.
1/3n-12= -10
+12 +12
_________
1/3n = +2
x3 x3
_________
n = 6
