I used a similar strategy, but assumed to puzzle maker was a nice person and each of the 13 x _ / 3 and _ x 6 / 9 resulted in a whole number.

I ended up with:

[6] + 13 x [3] / [1] + [9] + 12 x [2] - [5] - 11 + [8] x [7] / [4] - 10 = 66

Great snack btw.