How far is it from the moon and back?

Analyze and evaluate the motivation and the rationale behind western expansion through the louisiana purchase that took hold in the united states at the start of the 19th century (long essay question)

Which of the following activities would conserve the most energy? installing a dimmer switch on a light using a blender instead of a food processor hanging clothes to dry on a clothesline instead of ironing them opening a window instead of turning on the air conditioning setting your computer's screen saver to turn on after less time has elapsed

How do you do this? i’ve marked the correct answer but i can’t seem to calculate