#### Answer

$2.5 \times 10$

#### Work Step by Step

Divide the corresponding parts to obtain:
$=\dfrac{5}{20} \times \dfrac{10^{-6}}{10^{-8}}
\\=0.25 \times 10^{-6-(-8)}
\\=0.25 \times 10^{-6+8}
\\=0.25 \times 10^2$
Simplify to put the number in scientific notation.
$=2.5 \times 10^{2-1}
\\=2.5 \times 10^1
\\=2.5 \times 10$