[tex]1.x + y + z = 48 \\ \frac{x}{4} = \frac{y}{5} = \frac{z}{7} [/tex]
[tex]y = \frac{5x}{4} [/tex]
[tex]z = \frac{7x}{4} [/tex]
[tex]x + \frac{5x}{4} + \frac{7x}{4} = 48[/tex]
[tex] \frac{4x + 5x + 7x}{4} = \frac{192}{4} \\ 16x = 192 \\ x = 192 \div 16 = 12[/tex]
[tex]y = \frac{12 \times 5}{4} = 15[/tex]
[tex]z = \frac{7 \times 12}{4} = 21[/tex]
