<span>The book has sold 442,696 copies to date.
This was calculated by making a proportion: 8.9 : 39,400 = 100 : X where X Is the number of copies sold.
Then I calculated 39,400*100/8.9 to obtain the answer</span>
Given :
The foci of hyperbola are (8,0) and (-8,0) .
The difference of the focal radii = 6.
To Find :
The equation of the hyperbola.
Solution :
We know, distance between foci is given by :
2c = 8 - (-8)
c = 8
Also, difference between the foci or focal distance is given by :
2a = 6
a = 3
Now, we know for hyperbola :

General equation of hyperbola is :

Hence, this is the required solution.
Take the 2/5 and multiple it by 3 to get 6/15....then take the 1/3 and multiple it by 5 to get 5/15. Then add this together (6/15+5/15=....) to get 11/15
Alright, here is how to do it:
First you are going to want to multiply 4x4. [That is Dino's Charges for 4 Sandwiches.] So once you've done that, you should get 16
Now, you're going to want to multiply 8x4. [That is Carla's charges for 4 Sandwiches.] So once you've done that, you should get 24.
Now, to find the difference you will have to subtract them. 24-16 = 18.
Now that we've done this we now know your answer is:
Carla's sandwiches cost more than Dino's sandwiches. The difference is 18 dollars.
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I hope I helped, if I did; please give me brainliest. :)