Theorem difeq2d 3347

Description: Deduction adding difference to the left in a class equality. (Contributed by NM, 15-Nov-2002.)

Hypothesis

Ref	Expression
difeq1d.1	|- ( ph -> A = B )

Assertion

Ref	Expression
difeq2d	|- ( ph -> ( C \ A ) = ( C \ B ) )

Proof of Theorem difeq2d

Step	Hyp	Ref	Expression
1		difeq1d.1	. 2 |- ( ph -> A = B )
2		difeq2 3341	. 2 |- ( A = B -> ( C \ A ) = ( C \ B ) )
3	1, 2	syl 14	1 |- ( ph -> ( C \ A ) = ( C \ B ) )

Syntax hints:   -> wi 4   = wceq 1402   \ cdif 3217

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 623  ax-in2 624  ax-5 1500  ax-7 1501  ax-gen 1502  ax-ie1 1546  ax-ie2 1547  ax-8 1557  ax-11 1559  ax-4 1563  ax-17 1579  ax-i9 1583  ax-ial 1587  ax-i5r 1588  ax-ext 2220

This theorem depends on definitions:  df-bi 117  df-tru 1405  df-nf 1514  df-sb 1816  df-clab 2225  df-cleq 2231  df-clel 2234  df-ral 2533  df-rab 2537  df-dif 3222

This theorem is referenced by:  difeq12d  3348  exmid1stab  4340  phplem3  7145  phplem4  7146  phplem3g  7147  phplem4dom  7153  phplem4on  7159  fidifsnen  7162  xpfi  7229  sbthlem2  7265  sbthlemi3  7266  isbth  7274  ismkvnex  7485  ballotfilemfval  13207  setsvalg  13360  setsvala  13361