Let x equal the number of adult tickets sold.
X + 3X=512
(I put 3x because we know the students sold 3 times as many).
Solve for X.
X+3X=512
4X=512
4X/4=512/4
X=128
Answer: 
which is choice C
=====================================================
Explanation:
This is a 30-60-90 triangle. The short leg is 5, as it's opposite the smallest angle. The long leg is 
times that of the short leg.
You said 2x - 9 < 7
Add 9 to each side: 2x < 16
Divide each side by 2 : x < 8 .
Answer: 222cm
Step-by-step explanation:
To find the area of this composite shape you will have to split them into 2 shapes; a rectangle and a triangle.
To work out the area of the rectangle you have to do 15×12= 180
Then, to work out the area of the triangle, you use the formula base times height divided by 2.
7×12=84
84÷2=42
Then to work out the total area of both the rectangle and the triangle, you have to add the area of both.
180+42=222cm
Hope this helps :)
The best choice would be neither
