[tex]\dfrac{0.8\times 0.04}{0.5}\\\\\\=\dfrac{\tfrac 8{10} \times \tfrac 4{100}}{\tfrac 5{10}}\\\\\\=\dfrac{\tfrac 45 \times \tfrac 1{25}}{\tfrac 12}\\\\\\= \dfrac 4{125} \times 2\\\\\\=\dfrac 8{125}[/tex]