Answer:
D.3.5
Step-by-step explanation:
4x+2y=10(given)
2x+y=5
y=5-2x-----(1)
y=2x-1------(2)(given)
Since the left side of the equations are the the same,
5-2x=2x-1
4x=6
x=1.5
Sub x=1.5 into eq(1),
y = 5-2(1.5) = 5-3 = 2
so, x+y = 1.5+2 = 3.5
so their are 6 adults and 24 kids because when you add 18+6 and get 24
then you multiply 6(24) because adult tickets are 24 and get 144
then you multiply 24(12) because student tickets are half as much as parents so they are 12 and you multiply by 24 kids and get 288
then you add 288 student tickets total price +144 adult ticket total price =432 total cost fro all tickets
This is the process of completing the square.
Keep this equation in mind:

Basically, to make this a perfect square trinomial, you take half of b and square that value. This will make it so you can compress the left side of the equation into

depending on the sign in the middle of the original equation.
If 12 is shaded out of 18 then the fraction is 12/18. We then need to simplify it to get 2/3.
The answer is D) 2/3