You eliminate or ‘take away’ the answers that you know or think that r wrong. The last answer that’s left is your answer.
I would divide the 18000 by 13.26 to get the number of hours needed.
18000/13.26~169.7 days with 8 hour shifts.
X= 14 + 9y over 2
y= -x - 7 over 6
The answer is 14
-18/6 is -3. add that to 17 and you get 14.