[tex] \frac{x}{15} = 3 \frac{4}{5} \\ \\ \frac{x}{15} = \frac{3 \times 5 + 4}{5} \\ \\ \frac{x}{15} = \frac{15+4}{5} \\ \\ \frac{x}{15} = \frac{19}{5} \\ \\ x = \frac{19}{5} \times 15 \\ \\ x = \frac{285}{5} \\ \\ x = 57 \\ \\ Answer: \fbox {x = 57} [/tex]
