Step |
Hyp |
Ref |
Expression |
1 |
|
simp1 |
|- ( ( A e. RR /\ B e. RR /\ C e. RR ) -> A e. RR ) |
2 |
|
simp3 |
|- ( ( A e. RR /\ B e. RR /\ C e. RR ) -> C e. RR ) |
3 |
|
simp2 |
|- ( ( A e. RR /\ B e. RR /\ C e. RR ) -> B e. RR ) |
4 |
|
rersubcl |
|- ( ( B e. RR /\ C e. RR ) -> ( B -R C ) e. RR ) |
5 |
3 2 4
|
syl2anc |
|- ( ( A e. RR /\ B e. RR /\ C e. RR ) -> ( B -R C ) e. RR ) |
6 |
|
resubsub4 |
|- ( ( A e. RR /\ C e. RR /\ ( B -R C ) e. RR ) -> ( ( A -R C ) -R ( B -R C ) ) = ( A -R ( C + ( B -R C ) ) ) ) |
7 |
1 2 5 6
|
syl3anc |
|- ( ( A e. RR /\ B e. RR /\ C e. RR ) -> ( ( A -R C ) -R ( B -R C ) ) = ( A -R ( C + ( B -R C ) ) ) ) |
8 |
|
repncan3 |
|- ( ( C e. RR /\ B e. RR ) -> ( C + ( B -R C ) ) = B ) |
9 |
2 3 8
|
syl2anc |
|- ( ( A e. RR /\ B e. RR /\ C e. RR ) -> ( C + ( B -R C ) ) = B ) |
10 |
9
|
oveq2d |
|- ( ( A e. RR /\ B e. RR /\ C e. RR ) -> ( A -R ( C + ( B -R C ) ) ) = ( A -R B ) ) |
11 |
7 10
|
eqtrd |
|- ( ( A e. RR /\ B e. RR /\ C e. RR ) -> ( ( A -R C ) -R ( B -R C ) ) = ( A -R B ) ) |