How to analyze this diode circuit for a resistance?
I'm going to assume they want you to use the diode V-I equation which involves exponentials. They tell you a starting point of the diode at 0.7V at 1mA so you can find a set point on the diode curve. Then you'll have to solve the simultaneous equations (10-2.4)/R=Idiode and 2.4=3*Vdiode.

https://en.wikipedia.org/wiki/Diode_modelling#Shockley_diode_model
Vt of that equation is ~25 mV. Use the approximate equation since Vd>>nVt.

Really you'll end up with 3 equations to solve simultaneously. The first two I gave above. The last is the diode equation once you've found Is using 0.7V at 1mA.