Answer
Please see the work below.
Work Step by Step
We know that
$E=G\space m_E\space m(\frac{1}{r_1}-\frac{1}{r_2})$
We plug in the known values to obtain:
$E=(6.67\times 10^{-11})(5.97\times 10^{24})(\frac{1}{6.37\times 10^6}-\frac{1}{6.37\times 10^6+1800\times 10^3})$
$E=3.2\times 10^9J$
