Răspuns:
Explicație pas cu pas:
a+b+c= 120
a/4 =b/3 = c/13 =k
⇒a/4=k a= 4k
b/3=k b= 3k
c/13 =k c= 13k
4k+3k+13k =120
20k = 120 ⇒ k= 6
a=4k a=4*6 a=24
b=3k b= 3*6 b= 18
c=13k c= 13*6 c=78
Verificare : 24+18+78= 120
d)
a/5 =b/7 = c/12 =k
⇒ a/5=k a= 5k
b/7=k b=7k
c/12=k c=12k
5k+7k+12k=120
24k =120
k=5
a=5k a=5*5 a=25
b=7k b=7*5 b=35
c=12k c=12*5 c=60
Verificare : 25+35+60 =120