If there are 20 of my friends song prank other 30 of there friends and only 10 fell for it but 10 did not how many is = all together

20 + 30 = 50 people in total

So in the 30,10 people were pranked and 10 did not, that means the other 10 people did not even listen to them or something.

But it is for sure that there are 50 people in total over there.

I think that The answer is 50