there are 2.2lbs in 1kg, so, how many kg in 3.18lbs?
[tex]\bf \begin{array}{ccll}
lbs&kg\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
2.2&1\\
3.18&k
\end{array}\implies \cfrac{2.2}{3.18}=\cfrac{1}{k}\implies k=\cfrac{3.18\cdot 1}{2.2}[/tex]