Your friend needs one cup of homemade orange juice he squeezes 1/2 a cup of orange juice from one orange and 3/8 of a cup from Nana another orange does your friend need to squeeze another orange explain

answer:

No, your friend does not need another orange.

Step-by-step explanation:

+ =

is more than one cup.

Show this is false:  For each non-zero integer x there exists integer y such that xy=1

Let's take x=2, so our equation is

2y = 1

That has solution y=1/2 which isn't an integer, not in Z*.  There's no integer y that can solve this equation.  We found an x where the y doesn't exist, that's a counterexample to the claim.