Answer: John has nothing left to eat
Explanation:
Well if john has two burgers and he gives one to his friend 2-1=1
John now has one burger
But then he gives away 2/4 of the one
1-2/4=2/4
Now he has 2/4 of a burger
Then he gives 1/4 to his dad and 1/4 to his mom
2/4-1/4=1/4
1/4-1/4=0
John has nothing left he gave it all away :(