Răspuns :
a + b + c + d = 581
11 + b + c + d = 581
b + c + d = 581 - 11
b + c + d = 570
c = b +2
d = b + 4
b + b + 2 + b + 4 = 570
3 b + 6 = 570
3 b = 564
b = 564 : 3
b = 188
c = 188 + 2 = 190
d = 188 + 4 = 192
a + b + c + d = 581
11 + b + c + d = 581
b + c + d = 581 - 11
b + c + d = 570
c = b +2
d = b + 4
b + b + 2 + b + 4 = 570
3 b + 6 = 570
3 b = 564
b = 564 : 3
b = 188
c = 188 + 2 = 190
d = 188 + 4 = 192