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Metamath Proof Explorer

Theorem 3p1e4

Description: 3 + 1 = 4. (Contributed by Mario Carneiro, 18-Apr-2015)

Ref Expression
Assertion 3p1e4 ( 3 + 1 ) = 4

Proof

Step Hyp Ref Expression
1 df-4 ⊢ 4 = ( 3 + 1 )
2 1 eqcomi ⊢ ( 3 + 1 ) = 4