Theorem 7lt9

Description: 7 is less than 9. (Contributed by Mario Carneiro, 9-Mar-2015)

	Ref	Expression
Assertion	7lt9	$$⊢7<9$$

Proof

Step	Hyp	Ref	Expression
1		7lt8	$$⊢7<8$$
2		8lt9	$$⊢8<9$$
3		7re	$$⊢7\in ℝ$$
4		8re	$$⊢8\in ℝ$$
5		9re	$$⊢9\in ℝ$$
6	3 4 5	lttri	$$⊢\left(7<8\wedge 8<9\right)\to 7<9$$
7	1 2 6	mp2an	$$⊢7<9$$