31 pounds cost $93
Explanation
you can easily solve this by using a rule of three.
Step 1
Let x represents the cost for 31 pounds,the proportion is
[tex]\frac{x}{31}[/tex]Now
[tex]\begin{gathered} 24\text{ usd}\rightarrow8\text{ Pounds} \\ \text{the proportion must be the same, then} \\ \frac{24}{8}=\frac{x}{31} \\ 3=\frac{x}{31} \\ \end{gathered}[/tex]Step 2
solve for x
[tex]\begin{gathered} 3=\frac{x}{31} \\ x=3\cdot31 \\ x=93 \end{gathered}[/tex]Hence, 31 pounds cost $93
I hope this helps you