Theorem 4p4e8

Description: 4 + 4 = 8. (Contributed by NM, 11-May-2004)

	Ref	Expression
Assertion	4p4e8	$$⊢4+4=8$$

Proof

Step	Hyp	Ref	Expression
1		df-4	$$⊢4=3+1$$
2	1	oveq2i	$$⊢4+4=4+3+1$$
3		4cn	$$⊢4\in ℂ$$
4		3cn	$$⊢3\in ℂ$$
5		ax-1cn	$$⊢1\in ℂ$$
6	3 4 5	addassi	$$⊢4+3+1=4+3+1$$
7	2 6	eqtr4i	$$⊢4+4=4+3+1$$
8		df-8	$$⊢8=7+1$$
9		4p3e7	$$⊢4+3=7$$
10	9	oveq1i	$$⊢4+3+1=7+1$$
11	8 10	eqtr4i	$$⊢8=4+3+1$$
12	7 11	eqtr4i	$$⊢4+4=8$$