Răspuns :
(a+b+c+d+e):5=24 ⇒a+b+c+d+e=120
(a+b):2=15 ⇒a+b=30
a+b+c+d+e=120
30+c+d+e=120
c+d+e= 120-30
c+d+e=90
(c+d+e):3=30
(a+b):2=15 ⇒a+b=30
a+b+c+d+e=120
30+c+d+e=120
c+d+e= 120-30
c+d+e=90
(c+d+e):3=30