fist we have to add together the voltage from each diode of .7v plus .7volt= 1.4 volt
after we have the total voltage from the diodes now we can subtract the voltage form the source of 4v munus 1.4vol= 2.6volt
so then we use the formula of current
I=V/R
I 2.6v/5.1kΩ= 509 μA
