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Metamath Proof Explorer

Theorem 1e2m1

Description: 1 = 2 - 1. (Contributed by David A. Wheeler, 8-Dec-2018)

Ref Expression
Assertion 1e2m1 
|- 1 = ( 2 - 1 )

Proof

Step Hyp Ref Expression
1 2m1e1 
 |-  ( 2 - 1 ) = 1
2 1 eqcomi 
 |-  1 = ( 2 - 1 )