The goal of this game is to make 21. You have the four numbers 1, 5, 6 and 7 and you can use any combination of multiplication, addition, division, subtraction and bracketing. And that’s it, that’s all there is to it.

I know of one solution, and with a slightly charitable interpretation of the question found two more. There could be others.

**Edit:** Any solution must use each of the numbers 1, 5, 6 and 7 exactly once each