Metamath Proof Explorer


Theorem ltadd2d

Description: Addition to both sides of 'less than'. (Contributed by Mario Carneiro, 27-May-2016)

Ref Expression
Hypotheses ltd.1
|- ( ph -> A e. RR )
ltd.2
|- ( ph -> B e. RR )
letrd.3
|- ( ph -> C e. RR )
Assertion ltadd2d
|- ( ph -> ( A < B <-> ( C + A ) < ( C + B ) ) )

Proof

Step Hyp Ref Expression
1 ltd.1
 |-  ( ph -> A e. RR )
2 ltd.2
 |-  ( ph -> B e. RR )
3 letrd.3
 |-  ( ph -> C e. RR )
4 ltadd2
 |-  ( ( A e. RR /\ B e. RR /\ C e. RR ) -> ( A < B <-> ( C + A ) < ( C + B ) ) )
5 1 2 3 4 syl3anc
 |-  ( ph -> ( A < B <-> ( C + A ) < ( C + B ) ) )