2x=3y; 3y=5z\\ \\ =>2x=3y=5z\\ \\ =>y=\frac{2}{3}x;z=\frac{2}{5}x\\ \\ =>\frac{15x+10x+6x}{15}=310\\ \\ =>31x=310*15\\ =>x=150;y=\frac{2}{3}x=100;z=\frac{2}{5}x=60 " alt=" x+y+z=310\\ \\ \frac{x}{y}=\frac{12}{8};\frac{y}{z}=\frac{6,5}{3,9}\\ \\ =>2x=3y; 3y=5z\\ \\ =>2x=3y=5z\\ \\ =>y=\frac{2}{3}x;z=\frac{2}{5}x\\ \\ =>\frac{15x+10x+6x}{15}=310\\ \\ =>31x=310*15\\ =>x=150;y=\frac{2}{3}x=100;z=\frac{2}{5}x=60 " align="absmiddle" class="latex-formula">