The price of pebbles are 4.50/kg.
a) how many kilograms of pebbles can be bought with $10?

2.222222222222222222222222222222222222222222222222222222kg

or 2.2kg rounded :)

Step-by-step explanation:

10/4.50 = 2.2222222222222222222222222222222222222222222222222

so if you multiply both sides by 2.22222 you get (4.50 *2.222222 = 10)(kg*2.222222 = 2.222222222kg)

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.

only 10/60 isn't equivalent

hope this : )