I am Making a music video and If I shoot with the EX3 at 23.976 fps I would play back the song at double speed or 200% with the EX3 overcrank set to 48fps Doing this would make the video slow motion by 50%

QUESTION IS, If I still shoot at 23.976 but overcrank to 30fps what speed would the song have to play back at? what would the percent be? I know it would be faster than overcranking at 48fps

23,976 would be 100% - then 1% would be 23,976/100 = 0,23976
How many procent would 30 then be? 30/0,23976 = 125,125125 %

That would be 25 % faster - check calculating 25% of 24 is 6 - 24+6 is 30 so it seems to be right.
Hope you enjoy.

I'm impressed Bo, could you fit in my daughters Maths exam this week?

Absolutely - understanding math is better than just getting a equation.