Given the proportion:
[tex]k=\frac{\text{ reused}}{\text{ discarded}}[/tex]Assuming this proportion remains constant, then, using the values from the problem:
[tex]k=\frac{0.8\text{ million tons}}{7\text{ million tons}}=\frac{4}{35}[/tex]Now, if 17.5 million tons of clothing are discarded, we can use this ratio to calculate how many tons will be reused:
[tex]\begin{gathered} \frac{\text{ reused}}{17.5\text{ million tons}}=\frac{4}{35} \\ \\ \therefore\text{ reused }=2\text{ million tons} \end{gathered}[/tex]