Use order of operations (PEMDAS)
1. Open the parenthesis first, while opening the parenthesis take care of the minus sign outside the parenthesis. It is -1 outside the parenthesis. Using the distributive property distribute -1. Now the expression becomes
17 - 6 + 18/6 - 3
2. Solve the division next. Now the expression will be
17 - 6 + 3 - 3
3. Now add all positive numbers and add negative numbers.
20 - 9 = 11 (answer)
I hope this helps you.