Răspuns :
a+b+c=780
b=a+30
c=3a
a+a+30+3a=780
5a=780-30
a=750:5
a=150
b=150+30=180
c=3·150=450
b=a+30
c=3a
a+a+30+3a=780
5a=780-30
a=750:5
a=150
b=150+30=180
c=3·150=450