Theorem 8lt9

Description: 8 is less than 9. (Contributed by Mario Carneiro, 19-Feb-2014)

	Ref	Expression
Assertion	8lt9	|- 8 < 9

Proof

Step	Hyp	Ref	Expression
1		8re	|- 8 e. RR
2	1	ltp1i	|- 8 < ( 8 + 1 )
3		df-9	|- 9 = ( 8 + 1 )
4	2 3	breqtrri	|- 8 < 9