Calculating the values of gm and ro be

Question

Problem:

1. Show that when ro is taken into account, the voltage gain of the source follower becomes

Now, with RL removed, the voltage gain is carefully measured and found to be 0.98. Then, when RL is connected and its value is varied, it is found that the gain is halved at RL = 500 Ω. If the amplifier remained linear throughout this measurement, what must the values of gm and ro be?