Respuesta :

0.09 is the answer …

[tex]a^{-1}=\dfrac{1}{a}\\\\0.9\cdot10^{-1}=0.9\cdot\dfrac{1}{10}=\dfrac{0.9}{10}=\dfrac{0.9\cdot10}{10\cdot10}=\dfrac{9}{100}=0.09[/tex]