Răspuns :
a/3=b/5=c/7=k/1
a=3k b=5k c=7k
a+b+c=105
3k+5k+7k=105
15k=105
k=105:15
k=7 => a=3×7=21
b=5×7=35
c=7×7=49
Răspuns:
a,b,c d.p. cu 3,5,7
a/3=b/5=c/7=K
a=3k
b=5k
c=7k
a+b+c=105
3k+5k+7k=105
15k=105
k=105:15
k=7
a=3k=3×7=21
b=5k=7×5=35
c=7k=7×7=49
Verificare:21+35+49=105