d = 9 * 10^{10} m

v = 3 * 10^{8} m/s

B = 64 Mbps = 64 * 10^{6} bps

L = Frame size = 32 KB = 32 * 1024 * 8 bits

Throughput = Efficiency * Bandwidth

Efficiency = 1 / (1 + 2a)

Where, a = Tp / Tt

Propagation Time = Tp = d / v = 3 * 10^{2} = 300 sec

Transmission Time = Tt = Frame size / Bandwidth = 4096 * 10^{-6} sec

Substitute values of Tp and Tt in efficiency formula, You will get --

Efficiency = 6.826 * 10^{-6}