Refinery EM can produce 22 gallons of gasoline or 18 gallons of flight fuel per barrel of crude oil. Refinery CG can produce 18 gallons of gasoline or 16 gallons of flight fuel per barrel of crude oil. Does OUTPUT vary or does INPUT vary in this problem?

Output varies

Explanation:

Here the outputs of gallons of gasoline and flight fuel is mentioned of two refineries namely Refinery EM and Refinery CG. The output has been mentioned with respect to one barrel of crude oil. So, one barrel of crude is used by both the refineries.

So, here the output (gallons of gasoline and flight fuel) varies while the input (one barrel of crude oil) remains constant.

current and voltage can both be different in different parts of a circuit so it matters where you place the ammeter and voltmete