Răspuns :
(a+b+c)/3=18
a+b+c = 18x3
a+b+c=54
a=2b
c=2b+4
2b+b+2b+4=54
5b=54-4
5b=50
b=10
a=2x10
a=20
c=a+4
c=24
a+b+c = 18x3
a+b+c=54
a=2b
c=2b+4
2b+b+2b+4=54
5b=54-4
5b=50
b=10
a=2x10
a=20
c=a+4
c=24