# Thread: Proof help: equality of natural numbers

1. ## Proof help: equality of natural numbers

Thm 2: Suppose m, n eN are such that n >=m. Then n = m + b if and only if b = n -m.

THe problem:
If n, m e N with n >= m and n - m = 0, then n = m.

I am asked to prove this as a consequence of Thm. 2. Any adivce? THanks.

2. Originally Posted by jzellt
Thm 2: Suppose m, n eN are such that n >=m. Then n = m + b if and only if b = n -m.

THe problem:
If n, m e N with n >= m and n - m = 0, then n = m.

I am asked to prove this as a consequence of Thm. 2. Any adivce? THanks.
Use theorem 2, but let b=0...