(a+b+c+d)/4=91 ⇒ a+b+c+d=364
(a+b+c)/3 = 80 ⇒ a+b+c=240 inlocuim in prima egalitate si obtinem d=124
(a+b)/2=84 ⇒ a+b=168 inlocuim in a doua egalitate si obtinem c=72
a=c-16
a=72-16=56
d=364-124-72-56=112
b) a+b=1430
a=b+28
b+28+b=1430
2b=1402
b=701
a=701+28=729
c) (18+245+x)/3=336
18+245+x=336 x 3= 1008
x=1008-263=745