[tex] \frac{a+b+c}{3}= \frac{68}{3} \\
a+b+c=68 [/tex]
Numerele sunt d.p. cu 3,5,9 ==>
[tex] \frac{a}{3} = \frac{b}{5} = \frac{c}{9} =k \\
a=3k \\
b=5k \\
c=9k \\ [/tex]
Inlocuim:
[tex]3k+5k+9k=68 \\
17k=68 \\
k=4 \\
a=3*4=12 \\
b=5*4=20 \\
c=9*4=36[/tex]