Andrew has a cell phone plan that provides 300 free minutes each month for a flat rate of $19. for any minutes over 300, andrew is charged $0.39 per minute. which of the following piecewise functions represents charges based on andrew's cell phone plan?

Step-by-step explanation:

Andrew has a cell phone plan that provides 300 free minutes each month for a flat rate of $19. For any minutes over 300, Andrew is charged $0.39 per minute.

Let x be the number of minutes Andrew uses per month and f(x) be the charges based on Andrew's cell phone plan.

If then

If then first 300 minutes are free and each minute of next (x-300) minutes costs $0.39, therefore

Hence,

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.