[tex]\displaystyle\bf\\\frac{3\cdot 10^{6} \cdot 800}{0,5\cdot 10^{8} } =\frac{3\cdot 10^{6} \cdot 8\cdot 10^{2} }{0,5\cdot 10^{8} } =\frac{3\cdot 10^{6+2} \cdot 8}{0,5\cdot 10^{8} } =\\\\\\=\frac{3\cdot 10^{8} \cdot 8}{0,5\cdot 10^{8} }=\frac{3\cdot 8}{0,5} =24\cdot 2=48[/tex]