Theorem 2p7e9

Description: 2 + 7 = 9. (Contributed by SN, 24-Aug-2026)

	Ref	Expression
Assertion	2p7e9	$$⊢2+7=9$$

Proof

Step	Hyp	Ref	Expression
1		2cn	$$⊢2\in ℂ$$
2		5cn	$$⊢5\in ℂ$$
3	1 2 1	addassi	$$⊢2+5+2=2+5+2$$
4		2p5e7	$$⊢2+5=7$$
5	4	oveq1i	$$⊢2+5+2=7+2$$
6		7p2e9	$$⊢7+2=9$$
7	5 6	eqtri	$$⊢2+5+2=9$$
8		5p2e7	$$⊢5+2=7$$
9	8	oveq2i	$$⊢2+5+2=2+7$$
10	3 7 9	3eqtr3ri	$$⊢2+7=9$$