Answer
$\eta_{turbine}=\frac{W_{mecanic}}{W_{fluid}}$
$\eta_{generator}=\frac{W_{electric}}{W_{mecanic}}$
$\eta_{turbine-generator}=\frac{W_{electric}}{W_{fluid}}$
Work Step by Step
The turbine efficiency:
$\eta_{turbine}=\frac{W_{mecanic}}{W_{fluid}}$
The generator efficiency:
$\eta_{generator}=\frac{W_{electric}}{W_{mecanic}}$
Then the turbine-generator efficiency is:
$\eta_{turbine-generator}=\eta_{turbine}*\eta_{generator}=\frac{W_{electric}}{W_{fluid}}$
