Diodes. El led

R= V/I
R= 9/30= 0,3 Kohms= 300ohms

Vr1= Vt-Vled= Vr1= 9-2=7V I=V/R= 7/350=0,02Am·1000=20Am Vr2=Vt-Vled2=Vr2=9-2-2=5V: 500=0,01A=10mA