Răspuns :
|------|------|------|------| a
|------| b
a - b = 315
315 : 3 = 105 ( b )
105 x 4 = 420 ( a )
420 - 105 = 315
420 + 105 = 525
|------| b
a - b = 315
315 : 3 = 105 ( b )
105 x 4 = 420 ( a )
420 - 105 = 315
420 + 105 = 525