Răspuns :
a+b+c+d =300 b-a = c-b = d-c =30 a=b - 30 c = b+30 d = 30+ b+30 =60+b
b - 30 +b + b +30 + 60+b = 300
4b = 240 b = 60 a = 30 c = 90 d = 120
b - 30 +b + b +30 + 60+b = 300
4b = 240 b = 60 a = 30 c = 90 d = 120