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Metamath Proof Explorer

Theorem 8p7e15

Description: 8 + 7 = 15. (Contributed by Mario Carneiro, 19-Apr-2015)

		Ref	Expression
	Assertion	8p7e15	$⊢ 8 + 7 = 15$

Step	Hyp	Ref	Expression
1		8nn0	$⊢ 8 \in ℕ_{0}$
2		6nn0	$⊢ 6 \in ℕ_{0}$
3		4nn0	$⊢ 4 \in ℕ_{0}$
4		df-7	$⊢ 7 = 6 + 1$
5		df-5	$⊢ 5 = 4 + 1$
6		8p6e14	$⊢ 8 + 6 = 14$
7	1 2 3 4 5 6	6p5lem	$⊢ 8 + 7 = 15$