Rewrite the equation: 2y=x-6, y=x/2-3, so slope is 1/2 which is also the slope of the parallel line.
It will have the equation y=x/2+a where a is found by plugging in the given point: 4=-1+a, so a=5.
Therefore y=x/2+5. (This can also be written 2y=x+10 or x-2y+10=0)
If that helps, but I'm pretty sure the answer is -1 that is what I have found in Google that is what all the answers are that in finding.
The correct answer is 28 because all numbers add up to 200 and the number saying that she doesn't attend either is 56, half of 56 is 28. Voila