10 with a negative 4 as an exponent times 10 with a negative exponent... how would i work it? PLEASE HELP!

$10^{-4}\times 10^{-x}$

= $\dfrac{1}{10^4}\times \dfrac{1}{10^x}$

=$\dfrac{1}{10^4\times10^x}$

=$\dfrac{1}{10^{x+4}}$