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
6y + 12 = 3y - 3
Subtract 3y on both sides
3y + 12 = -3
Subtract 12 on both sides
3y = -15
Divide by 3 on both sides
y = -5
I think u should check the first one again u made a mistake but the second one is correct if u need any more help ask me