Using each of the digits 1, 2, 3, 4, 5, 6,7, 8, 9 only once... solve this problem.

x x x x x
- x x x x
3 3 3 3 3

This question was asked to Dom and me through my little brother's DS Game (Professor Layton and the Curious Village) and it took us a ridiculously long amount of time to solve it.
There has got to be some easier way to do it that we were both overlooking.
Dom ultimately got it because he's awesome.. but if you know an easy way to find the answer... do share. Please and thank you, of course.

I must have figured it out at one point, because I've beaten every puzzle in Professor Layton... don't remember how and I'm lazy right now.

Wow. I'm impressed.
That one took us forever.

My little bro only asked for help on a few of them.. but we even got fed up and quit playing when we couldn't figure out this 7 box question.