Răspuns:
11 a;b;c-nr direct prop cu 2 4 7
=> a/2=b/4=c/7=k
=> a=2k
b=4k
c=7k
c-a=60
7k-2k=60
5k=60
k=12
a=24
b=12×4=48
c=12×7=84
13.
=> a/1/2=b/1/5=c/1/6=k
=> a=k/2
b=k/5
c=k/6
k/2-k/5=15
5k/10-2k/10=15
3k/10=15
k=15×10/3
k=50
a=25
b=10
c=50/6=25/3
Sper ca e bine eventual poti sa mai corectezi