Can someone help me with a problem concerning Olbers' Paradox?

It is incorrectly argued that the inverse square law (F = L/(4pi*r^2) can provide a solution to Olbers’s paradox. To see that this is not correct, consider a uniform distribution of stars with n stars per unit volume, each of luminosity L. Imagine that two thin, spherical shells of stars with radii r1 and r2 are centered on Earth; let the thickness of each shell be Δr. Show that the same energy flux reaches Earth from each shell.