@CPhill @Anyone who knows math???

It is asking you to continue the pattern which in this case means that the top term is being multiplied by three while the bottom term is being divided by 2.

I am NO expert at this, but I think I found the original binomial,

and putting that into WolframAlpha gives the answer:

http://www.wolframalpha.com/input/?i=expand:+(x%2F2-1%2Fy)%5E7

Someone else can probably explain this the right way !! Haha 

x^7 / 128 - 7x^6 / (64y)  +  21x^5 /  (32y^2)  - ......... -  1 / y^7   

This is the binomial expansion  of

( x / 2   -   1 / y)^7

We have

C(7,0) (x/2)^7  -  C(7, 1) (x/2)^6 (1/y)  + C(7,2) (x /2)^5 (1/y)^2  -  ..... -  C(7,7) (1/y)^7