divide and write the result using scientific notation (4.0 x 10^7) / (5.0 x 10^9)

divide and write the result using scientific notation (4.0 x 10^7) / (5.0 x 10^9)

$$\small{\text{
$
\begin{array}{rcl}
\dfrac{4.0 \cdot 10^7} {5.0 \cdot 10^9} & \\
&=& \dfrac{4.0}{5.0} \cdot 10^7\cdot 10^{-9} \\
&=& 0.8 \cdot 10^{7-9} \\
&=& 0.8 \cdot 10^{-2} \\
&=& \dfrac{8}{10} \cdot 10^{-2} \\
&=& 8 \cdot \dfrac{ 10^{-2}}{10} \\
&=& 8 \cdot 10^{-2}\cdot 10^{-1} \\
&=& 8 \cdot 10^{-2-1} \\
&=& 8 \cdot 10^{-3 }
\end{array}
$}}$$

40000000/5000000000=0.08

4/5= 0.8

7-9=-2

0.8*(10^-2)=8*(10^-3)=0.08.