An individual white LED (light-emitting diode) has an efficiency of 20% and uses 1.0 WW of electric power. You may want to review Ch. 11-1. Part A How many LEDs must be combined into one light source to give a total of 1.6 WW of visible-light output (comparable to the light output of a 40 WW incandescent bulb)? Express your answer as an integer.