You can use bodmas to help work this out. bodmas is the order you should do stuff in these sorts to questions, the order goes: brackets, orders, division, multiplication, addition, subtraction.
This can be used in this case to solve it in this order;
Division:
81/27 = 3
3*6-2
Then multiplication:
3*6 = 18
18-2
Then finally subtraction:
18-2 = 16
The answer is 16,
Hope this helps! :)