The graph of an equation

sqrt((x-3)^2+(y+4)^2) + sqrt((x+5)^2+(y-8)^2)=20

is an ellipse. What is the distance between its foci?

\(\sqrt{(x-3)^2+(y+4)^2} + \sqrt{(x+5)^2+(y-8)^2}=20\\~\\ \)

Sorry, i have no idea.

Here you can see the simplified version

https://www.wolframalpha.com/input/?i=sqrt((x-3)%5E2%2B(y%2B4)%5E2)+%2B+sqrt((x%2B5)%5E2%2B(y-8)%5E2)%3D20

Thanks for the help! I got the answer to the problem after a lot of work.