Kelly flies a distance of 2,100 miles. The trip takes 4 hours. A. What is the airplane's unit rate of speed in miles per hour?
B. At this rate of speed, how many miles will the airplane travel in 13 hours?

A: The plane is going 525 miles per hour.

B: In 13 hours the plane will travel 6,825 miles.

Step-by-step explanation:

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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.