Answer
$6.73\times 10^{-21}ft$
Work Step by Step
We can find the required distance as follows:
$x_{cm}=\frac{m_1x_1+m_2x_2}{m_1+m_2}$
We plug in the known values to obtain:
$0 ft=\frac{(72.5Kg)(555ft)+(5.97\times 10^{24}Kg)x_2}{72.5Kkg+5.97\times 10^{24}Kg}$
$x_2=6.73\times 10^{-21}ft$
