[slimslim]

A+b=231
pgcd(a ,b)=21
a/21+b/21=231/21
a/21=x b/21=y pgcd(x,y)=1
x+y=11
(x ,y) (0,11) (1 ,10) (2,9) (3,8) (4,7) (5,6)
(a ;b) (0 ;231) (21 ;210) (42 189) (63 ; 168) (84 147) (105 ; 126)