Input:
2.83v x 85 mA = 240.6 mW

Output for leds only, with dividing resistors in circuit:
2 leds x 25 mA x 3.45v = 172.5 mW

efficiency = 172.5 / 240.6 = .717

Including dividing resistors in output load:
dV through resistor = .025 A x 10 ohms = .25 volts

2 leds x 25 mA x 3.70v = 185.0 mW

efficiency = 185.0 / 240.6 = .769