Metamath Proof Explorer


Theorem congsub

Description: If two pairs of numbers are componentwise congruent, so are their differences. (Contributed by Stefan O'Rear, 2-Oct-2014)

Ref Expression
Assertion congsub ABCDEABCADEAB-D-CE

Proof

Step Hyp Ref Expression
1 simp11 ABCDEABCADEA
2 simp12 ABCDEABCADEB
3 simp13 ABCDEABCADEC
4 simp2l ABCDEABCADED
5 4 znegcld ABCDEABCADED
6 simp2r ABCDEABCADEE
7 6 znegcld ABCDEABCADEE
8 simp3l ABCDEABCADEABC
9 simp3r ABCDEABCADEADE
10 congneg ADEADEA-D-E
11 1 4 6 9 10 syl22anc ABCDEABCADEA-D-E
12 congadd ABCDEABCA-D-EAB+D-C+E
13 1 2 3 5 7 8 11 12 syl322anc ABCDEABCADEAB+D-C+E
14 2 zcnd ABCDEABCADEB
15 4 zcnd ABCDEABCADED
16 14 15 negsubd ABCDEABCADEB+D=BD
17 3 zcnd ABCDEABCADEC
18 6 zcnd ABCDEABCADEE
19 17 18 negsubd ABCDEABCADEC+E=CE
20 16 19 oveq12d ABCDEABCADEB+D-C+E=B-D-CE
21 13 20 breqtrd ABCDEABCADEAB-D-CE