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Theorem nppcan2 7242
Description: Cancellation law for subtraction. (Contributed by NM, 29-Sep-2005.)
Assertion
Ref Expression
nppcan2  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  (
( A  -  ( B  +  C )
)  +  C )  =  ( A  -  B ) )

Proof of Theorem nppcan2
StepHypRef Expression
1 addcl 7006 . . . 4  |-  ( ( B  e.  CC  /\  C  e.  CC )  ->  ( B  +  C
)  e.  CC )
213adant1 922 . . 3  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  ( B  +  C )  e.  CC )
3 subsub 7241 . . 3  |-  ( ( A  e.  CC  /\  ( B  +  C
)  e.  CC  /\  C  e.  CC )  ->  ( A  -  (
( B  +  C
)  -  C ) )  =  ( ( A  -  ( B  +  C ) )  +  C ) )
42, 3syld3an2 1182 . 2  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  ( A  -  ( ( B  +  C )  -  C ) )  =  ( ( A  -  ( B  +  C
) )  +  C
) )
5 pncan 7217 . . . 4  |-  ( ( B  e.  CC  /\  C  e.  CC )  ->  ( ( B  +  C )  -  C
)  =  B )
653adant1 922 . . 3  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  (
( B  +  C
)  -  C )  =  B )
76oveq2d 5528 . 2  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  ( A  -  ( ( B  +  C )  -  C ) )  =  ( A  -  B
) )
84, 7eqtr3d 2074 1  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  (
( A  -  ( B  +  C )
)  +  C )  =  ( A  -  B ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ w3a 885    = wceq 1243    e. wcel 1393  (class class class)co 5512   CCcc 6887    + caddc 6892    - cmin 7182
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-in1 544  ax-in2 545  ax-io 630  ax-5 1336  ax-7 1337  ax-gen 1338  ax-ie1 1382  ax-ie2 1383  ax-8 1395  ax-10 1396  ax-11 1397  ax-i12 1398  ax-bndl 1399  ax-4 1400  ax-14 1405  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428  ax-ext 2022  ax-sep 3875  ax-pow 3927  ax-pr 3944  ax-setind 4262  ax-resscn 6976  ax-1cn 6977  ax-icn 6979  ax-addcl 6980  ax-addrcl 6981  ax-mulcl 6982  ax-addcom 6984  ax-addass 6986  ax-distr 6988  ax-i2m1 6989  ax-0id 6992  ax-rnegex 6993  ax-cnre 6995
This theorem depends on definitions:  df-bi 110  df-3an 887  df-tru 1246  df-fal 1249  df-nf 1350  df-sb 1646  df-eu 1903  df-mo 1904  df-clab 2027  df-cleq 2033  df-clel 2036  df-nfc 2167  df-ne 2206  df-ral 2311  df-rex 2312  df-reu 2313  df-rab 2315  df-v 2559  df-sbc 2765  df-dif 2920  df-un 2922  df-in 2924  df-ss 2931  df-pw 3361  df-sn 3381  df-pr 3382  df-op 3384  df-uni 3581  df-br 3765  df-opab 3819  df-id 4030  df-xp 4351  df-rel 4352  df-cnv 4353  df-co 4354  df-dm 4355  df-iota 4867  df-fun 4904  df-fv 4910  df-riota 5468  df-ov 5515  df-oprab 5516  df-mpt2 5517  df-sub 7184
This theorem is referenced by:  subsub4  7244  nppcan2d  7348
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