Question

If p and r are positive integers and 2p+r-1=2r+p+1, which of the following must be true
I. p and r are consecutive integers
II.p is even
III. r is odd

Answer 1

2p+r-1=2r+p+1
p-r=2

Answer 2

what's the 4th option?

Answer 3

They're either both odd consecutive or both even consecutive

Answer 4

Numbers of the same parity, as they say.

Answer 5

1,3
2,4
the difference is 2 in each case