You are using an electric motor that requires 40 volts to operate. The motor's circuit uses only 5 amps of direct current. How much power is being used?

The simplest formula for electrical power is               Power  =  (voltage) x (current) .You stated both of these quantities in the question.       Power  =  (40 volts) x (5 amperes)  =  200 watts .

40 volts multiplicated by 5 amps will give you a total of 200 watts