TeX source:
\begin{array}{rclcl} 100\;\% &\widehat{=}& 450 \;\text{kg} \cr\cr 1 \,\% &\widehat{=}& \dfrac{450}{100} \;\text{kg} \cr\cr 85 \;\% &\widehat{=}& \dfrac{85 \cdot 450 \;\text{kg}}{100} &=& 382{,}5 \;\text{kg} \end{array}