[tex] \frac{a+b+c}{3} =36=\ \textgreater \ a+b+c=36*3=\ \textgreater \ a+b+c=108 \\ \\ a= \frac{b}{3} =\ \textgreater \ b=3a \\ \\ a= \frac{c}{5} =\ \textgreater \ c=5a \\ \\ a+3a+5a=108 \\ 9a=108=\ \textgreater \ a=108:9=\ \textgreater \ a=12 \\ b=3*12=\ \textgreater \ b=36 \\ c=5*12=\ \textgreater \ c=60[/tex]