Answer:
x = 3
Step-by-step explanation:
We can solve this by using ratios of similar triangles
3 x
------ = ------------
3+9 12
3 x
------ = ------------
12 12
x must equal 3 to keep the ratios the same
Given:
A parabola opens up or down and its vertex is at the point (h, v).
To find:
The equation of the parabola.
Solution:
A parabola opens up or down. It means it is a vertical parabola.
The vertex form of a vertical parabola is
...(i)
Where, a is constant and (h,k) is vertex.
The vertex of given parabola is at point (h,v). Putting h=h and k=v in (i), we get

The required equation of the parabola is
.
Therefore, the correct option is A.
The total number of fish bought was 320. And you know she bought two types of fish. The best way to solve this is guess and check. It would be the fastest. So she bought 7 times as many trigger-fish as parrot fish that means the number of trigger-fish bought was 7p. This means 320 = 7p +p. So all you do is take educated guesses for the number of parrot fish and check if it is right. So if she bought 50 parrot fish. 7(50) + 50 = 400. Close but a bit high. Lets keep guessing. 7(35) + 35 = 245. So now we know the answer is between 50 and 35. So lets try 40. 7(40) + 40 =320. That works so we know she bought 40 parrot fish and 280 trigger-fish.