efficiency = use-full time / total time ===> Tt / Tt +2 Tp
Divide the complete formula with Tt ===> Efficiency = 1/1+2a consider Tp/Tt =a
Throughput also called as effective bandwidth or bandwidth utilization
in CN throughput =no of bits we are able to send per sec if L is the no of bit then
Throughput =L / Tt + 2 Tp (total cycle time)
Tt + 2 Tp is the total cycle time in which we are able to send L bits
Now multiply and divide L with Bandwidth(B) in formula L*(B/B) / Tt + 2 Tp
Now L / B =Tt So it will become Tt*B / Tt + 2 Tp
Now divide the formula with Tt then you get
(1/1+2a) * B ===> efficiency * bandwidth (I have given efficiency formula at the starting)
Throughput= efficiency * Bandwidth
if you dont understand it here write it down of a paper the you will understand .Try to do it by yourself