You buy 3 pairs of jeans for $35.95 each and get a fourth pair for free. what is your cost per pair of jeans

   Your cost per pair of jeans is $26.9625

Step-by-step explanation:

You buy 3 pairs of jeans for $35.95 each. So, the total cost will be:  

Now, you got a fourth pair of jeans for free. That means, actually you're buying 4 pairs of jeans for total $107.85

So, your cost per pair of jeans will be:  

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.