Theorem subsub4 8471

Description: Law for double subtraction. (Contributed by NM, 19-Aug-2005.) (Revised by Mario Carneiro, 27-May-2016.)

Assertion

Ref	Expression
subsub4	|- ( ( A e. CC /\ B e. CC /\ C e. CC ) -> ( ( A - B ) - C ) = ( A - ( B + C ) ) )

Proof of Theorem subsub4

Step	Hyp	Ref	Expression
1		nppcan2 8469	. 2 |- ( ( A e. CC /\ B e. CC /\ C e. CC ) -> ( ( A - ( B + C ) ) + C ) = ( A - B ) )
2		simp1 1024	. . . 4 |- ( ( A e. CC /\ B e. CC /\ C e. CC ) -> A e. CC )
3		simp2 1025	. . . 4 |- ( ( A e. CC /\ B e. CC /\ C e. CC ) -> B e. CC )
4		subcl 8437	. . . 4 |- ( ( A e. CC /\ B e. CC ) -> ( A - B ) e. CC )
5	2, 3, 4	syl2anc 411	. . 3 |- ( ( A e. CC /\ B e. CC /\ C e. CC ) -> ( A - B ) e. CC )
6		simp3 1026	. . 3 |- ( ( A e. CC /\ B e. CC /\ C e. CC ) -> C e. CC )
7	3, 6	addcld 8258	. . . 4 |- ( ( A e. CC /\ B e. CC /\ C e. CC ) -> ( B + C ) e. CC )
8		subcl 8437	. . . 4 |- ( ( A e. CC /\ ( B + C ) e. CC ) -> ( A - ( B + C ) ) e. CC )
9	2, 7, 8	syl2anc 411	. . 3 |- ( ( A e. CC /\ B e. CC /\ C e. CC ) -> ( A - ( B + C ) ) e. CC )
10		subadd2 8442	. . 3 |- ( ( ( A - B ) e. CC /\ C e. CC /\ ( A - ( B + C ) ) e. CC ) -> ( ( ( A - B ) - C ) = ( A - ( B + C ) ) <-> ( ( A - ( B + C ) ) + C ) = ( A - B ) ) )
11	5, 6, 9, 10	syl3anc 1274	. 2 |- ( ( A e. CC /\ B e. CC /\ C e. CC ) -> ( ( ( A - B ) - C ) = ( A - ( B + C ) ) <-> ( ( A - ( B + C ) ) + C ) = ( A - B ) ) )
12	1, 11	mpbird 167	1 |- ( ( A e. CC /\ B e. CC /\ C e. CC ) -> ( ( A - B ) - C ) = ( A - ( B + C ) ) )

Syntax hints:   -> wi 4   <-> wb 105   /\ w3a 1005   = wceq 1398   e. wcel 2202  (class class class)co 6028   CCcc 8090   + caddc 8095   - cmin 8409

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 619  ax-in2 620  ax-io 717  ax-5 1496  ax-7 1497  ax-gen 1498  ax-ie1 1542  ax-ie2 1543  ax-8 1553  ax-10 1554  ax-11 1555  ax-i12 1556  ax-bndl 1558  ax-4 1559  ax-17 1575  ax-i9 1579  ax-ial 1583  ax-i5r 1584  ax-14 2205  ax-ext 2213  ax-sep 4212  ax-pow 4270  ax-pr 4305  ax-setind 4641  ax-resscn 8184  ax-1cn 8185  ax-icn 8187  ax-addcl 8188  ax-addrcl 8189  ax-mulcl 8190  ax-addcom 8192  ax-addass 8194  ax-distr 8196  ax-i2m1 8197  ax-0id 8200  ax-rnegex 8201  ax-cnre 8203

This theorem depends on definitions:  df-bi 117  df-3an 1007  df-tru 1401  df-fal 1404  df-nf 1510  df-sb 1811  df-eu 2082  df-mo 2083  df-clab 2218  df-cleq 2224  df-clel 2227  df-nfc 2364  df-ne 2404  df-ral 2516  df-rex 2517  df-reu 2518  df-rab 2520  df-v 2805  df-sbc 3033  df-dif 3203  df-un 3205  df-in 3207  df-ss 3214  df-pw 3658  df-sn 3679  df-pr 3680  df-op 3682  df-uni 3899  df-br 4094  df-opab 4156  df-id 4396  df-xp 4737  df-rel 4738  df-cnv 4739  df-co 4740  df-dm 4741  df-iota 5293  df-fun 5335  df-fv 5341  df-riota 5981  df-ov 6031  df-oprab 6032  df-mpo 6033  df-sub 8411

This theorem is referenced by:  sub32  8472  nnncan  8473  pnpcan  8477  addsub4  8481  subsub4d  8580  2shfti  11471  nn0seqcvgd  12693