[tex] \frac{x}{6}= \frac{y}{9}= \frac{z}{15}\;\\
a)\;din\; \frac{x}{6}=\frac{z}{15}\leftrightarrow\;\\
\frac{x}{z}=\frac{6}{15}=40^o/_o\;;\\
b)\;din\;\frac{y}{9}=\frac{z}{15}=\frac{y+z}{24}\;;\\
din:\;\;\frac{x}{6}=\frac{y+z}{24}\;\\
obtinem :\;\;\frac{x}{y+z}=\frac{6}{24}=25/100[/tex]