The output of this opamp is two complimentary darlington transistors. They saturate with a loss of about 1.2V without a load and with a loss of 2.5V with a 9mA load.
The question says the opamp has only a 2% saturation voltage loss so the output high voltage is 98% of 9V. Calculate it.
The output high voltage feeds the LED through the current -limiting resistor.
You know the calculated output high voltage from the opamp and you know the voltage of the LED so then subtract the LED voltage from the output high voltage of the opamp to determine the voltage across the current-limiting resistor.
Then use Ohm's Law to calculate the value of the resistor.
Easy.