congruencies

2x =[2]= n <==> 2x = 2k+n <==> x = k+(n+(-p))[+]p

2x =[2]= 7 <==> 2x = 2k+7 <==> x = k+6[+]1 = k+5[+]2 = k+4[+]3

4x =[4]= 2n <==> 4x = 4k+2n <==> x = k+(n+(-q))[+](n+(-p))[+]q[+]p

4x =[4]= 14 <==> 4x = 4k+14 <==> ...

... x = k+5[+]6[+]2[+]1 = k+4[+]6[+]3[+]1 = k+4[+]5[+]3[+]2