Răspuns :
(a+b+c)/3=21
(a+b)/2=25=>a+b=2*25=50
c=2b-7
(50+2b-7)/3=21
50+2b-7=21*3
50+2b-7=63
2b=63-50+7
2b=20
b=20:2
b=10
(a+10)/2=25
a+10=50
a=50-10
a=40
c=20-7
c=13
Dem:(40+10+13)/3=63/3=21
(a+b)/2=25=>a+b=2*25=50
c=2b-7
(50+2b-7)/3=21
50+2b-7=21*3
50+2b-7=63
2b=63-50+7
2b=20
b=20:2
b=10
(a+10)/2=25
a+10=50
a=50-10
a=40
c=20-7
c=13
Dem:(40+10+13)/3=63/3=21
a+b+c/3=21 a+b+c=62
a+b=25 a+b=50
c=2a-7
c=62-50=12
2a=12+7=19
a=9,5
b=63-(12+9,5)=41,5