| Step | Hyp | Ref | Expression | 
						
							| 1 |  | f1ocpbl.f |  |-  ( ph -> F : V -1-1-onto-> X ) | 
						
							| 2 |  | f1of1 |  |-  ( F : V -1-1-onto-> X -> F : V -1-1-> X ) | 
						
							| 3 | 1 2 | syl |  |-  ( ph -> F : V -1-1-> X ) | 
						
							| 4 | 3 | adantr |  |-  ( ( ph /\ ( A e. K /\ B e. V /\ C e. V ) ) -> F : V -1-1-> X ) | 
						
							| 5 |  | simpr2 |  |-  ( ( ph /\ ( A e. K /\ B e. V /\ C e. V ) ) -> B e. V ) | 
						
							| 6 |  | simpr3 |  |-  ( ( ph /\ ( A e. K /\ B e. V /\ C e. V ) ) -> C e. V ) | 
						
							| 7 |  | f1fveq |  |-  ( ( F : V -1-1-> X /\ ( B e. V /\ C e. V ) ) -> ( ( F ` B ) = ( F ` C ) <-> B = C ) ) | 
						
							| 8 | 4 5 6 7 | syl12anc |  |-  ( ( ph /\ ( A e. K /\ B e. V /\ C e. V ) ) -> ( ( F ` B ) = ( F ` C ) <-> B = C ) ) | 
						
							| 9 |  | oveq2 |  |-  ( B = C -> ( A .+ B ) = ( A .+ C ) ) | 
						
							| 10 | 9 | fveq2d |  |-  ( B = C -> ( F ` ( A .+ B ) ) = ( F ` ( A .+ C ) ) ) | 
						
							| 11 | 8 10 | biimtrdi |  |-  ( ( ph /\ ( A e. K /\ B e. V /\ C e. V ) ) -> ( ( F ` B ) = ( F ` C ) -> ( F ` ( A .+ B ) ) = ( F ` ( A .+ C ) ) ) ) |