Theorem 8p2e10

Description: 8 + 2 = 10. (Contributed by NM, 5-Feb-2007) (Revised by Stanislas Polu, 7-Apr-2020) (Revised by AV, 6-Sep-2021)

	Ref	Expression
Assertion	8p2e10	$$⊢8+2=10$$

Proof

Step	Hyp	Ref	Expression
1		df-2	$$⊢2=1+1$$
2	1	oveq2i	$$⊢8+2=8+1+1$$
3		8cn	$$⊢8\in ℂ$$
4		ax-1cn	$$⊢1\in ℂ$$
5	3 4 4	addassi	$$⊢8+1+1=8+1+1$$
6	2 5	eqtr4i	$$⊢8+2=8+1+1$$
7		df-9	$$⊢9=8+1$$
8	7	oveq1i	$$⊢9+1=8+1+1$$
9		9p1e10	$$⊢9+1=10$$
10	6 8 9	3eqtr2i	$$⊢8+2=10$$