From Stefan law, the energy radiated by sun is given by. $P=\sigma eA{T}^4$, assuming e = 1 for sun.

In Ist case, $P_1=\sigma e\times 4\pi R^2\times T^4$

In 2nd case, $P_2=\sigma e\times 4\pi \left(2R^2\right)\times \left(2T^4\right)$

                        $= \sigma e\times 4\pi R^2\times T^4\times 64=64P_1$

The rate at which energy is received by earth is,

$E=\frac{P}{4\pi R_{SE}^2}\times A_E$

where A_E = area of earth

R_SE = distance between sun and earth

So, In Ist case, $E_1=$ $\frac{P_1}{4\pi R_{SE}^2}\times A_E$

                        $E_2=\frac{P_2}{4\pi R_{SE}^2}\times A_E=64E_1$