Sam is 10 years younger than one-half the age of his aunt. Let a represent his aunt’s age. Which algebraic expression can be used to determine Sam’s age if his aunt is 40?

Sam is 10 years old

Step-by-step explanation:

Sam is 10 years old because 20 is half of 40 and 20 subtract 10 is 10

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.