Theorem 7p6e13

Description: 7 + 6 = 13. (Contributed by Mario Carneiro, 19-Apr-2015)

	Ref	Expression
Assertion	7p6e13	⊢ ( 7 + 6 ) = ; 1 3

Proof

Step	Hyp	Ref	Expression
1		7nn0	⊢ 7 ∈ ℕ0
2		5nn0	⊢ 5 ∈ ℕ0
3		2nn0	⊢ 2 ∈ ℕ0
4		df-6	⊢ 6 = ( 5 + 1 )
5		df-3	⊢ 3 = ( 2 + 1 )
6		7p5e12	⊢ ( 7 + 5 ) = ; 1 2
7	1 2 3 4 5 6	6p5lem	⊢ ( 7 + 6 ) = ; 1 3