Summation inside a summation inside a summation

[qwerty12345]

I know how to do it normally, but this confuses me. Can you show me how to do it? And what were the steps you took... etc. Initially, I thought of putting them inside brtackets and work out the last one at the right first, but I'd need to know what K and J are, it's confusing. Can anyone make this clear for me?



EDIT:

I tried this, but it doesn't seem like I'm on the right track.

 

[qwerty12345]

But I also solved it with a calculator and it says the answer is 81. What am I doing wrong?

 

[qwerty12345]

Nevermind. I figured it out. :D

 

[SammyS]

1-1+1 = 1 not -1 ... that's if you mean i - j + k and not i - (j + k) .