Ethan invested £500 in the bank for 2 years.
he earned £40 simple interest in total.

what was the simple interest rate per annum

Step-by-step explanation:

I=PRT/100

40=(500XRX2)/100

R=(40X100)/500X2

R=4000/1000

R=4 percent/annum

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.

c

step-by-step explanation: