Answer
Please see the work below.
Work Step by Step
We know that the initial energy of the block is given as
$E_i=U+K=U+0=U=\frac{-GM_Em}{R_E}$
We plug in the known values to obtain:
$E_i=\frac{-(6.67\times 10^{-11})(5.97\times 10^{24})(1)}{6.37\times 10^6}=-6.2512\times 10^7J$
The final energy is given as
$E_f=\frac{-GM_Em}{2r}$
We plug in the known values to obtain:
$E_f=\frac{-(6.67\times 10^{-11})(5.97\times 10^{24})(1)}{(2)(4.22\times 10^7)}=-4.718\times 10^6J$
Now we can find the required energy as
$\Delta E=(-4.718\times 10^6)-(-6.2512\times 10^7)=5.8\times 10^7J$