
Wow, bcs I love science, I tried so hard on understanding what they were saying, and I kinda got it. It's about how you find the 'ground zero'(the starting point) of the 'wave'(that turns human into stone) using these informations :
- the wave is 20000 metres tall
- takes only 56 seconds to move as far as 500km
- that means it's moving about 32000 km per hour
From all that, they got the distance of the 'wave's ground zero' from both of their place(Xeno and Senku's place) which is 8181km. You just hv to make a triangle between Senku's place, Xeno's place and the 'wave's ground zero' on the earth's globe model (but Senku and Xeno use longitude and wtv so that it is more accurate), then you will get the wave's starting point or what Xeno said : ground zero.
That's where they're going!

There's a correction. You can't draw the triangle on the globe like I said there, sorry what Xeno said about 8181km is; for example if the distance of Senku's place and the ground zero is 10000km, then the distance of Xeno's place and ground zero is 18181km. They need the longitude or angle or wtv is that to find the exact place of the wave's ground zero.
No one :
Kang Moo : LEE KIRIN