Respuesta :

[tex]a\equiv b\mod n[/tex] means there is some integer [tex]N[/tex] such that [tex]a=Nn+b[/tex]. Multiplying everything by [tex]c[/tex] gives [tex]ca=cNn+cb=N(cn)+cb[/tex], which is the same as saying [tex]ca\equiv cb\mod cn[/tex].