Question 1075792
Let {{{alpha}}} be the percent of shading for both circles. 
If it was fully shaded, {{{alpha=1}}}.
If it was not shaded at all, {{{alpha=0}}}
1.{{{A[1]=alpha*((pi*D[1]^2)/4)}}}
2.{{{A[2]=alpha*((pi*D[2]^2)/4)}}}
From eq. 1,
{{{alpha=(4*A[1])/(pi*D[1]^2)}}}
Substituting into eq. 2,
{{{A[2]=((4*A[1])/(pi*D[1]^2))*((pi*D[2]^2)/4)}}}
{{{A[2]=A[1]*(D[2]^2/D[1]^2))}}}
{{{highlight(A[2]=A[1]*(D[2]/D[1])^2)}}}