Consider a 2.75W electric clock.
A.) What is the yearly cost, in dollars, of operating such a clock if the cost of electricity is $0.085 per kW⋅h ?
4 Answers

n = 24*365 hours
cost = 2.75/1000*n = 24*365*2.75/1000*0.085 = 2 $ ; 5 cents per year

Given 2.75w, start there and apply converters:
2.75 w (1kw/1000w) ($0.085/kW⋅h) (24hr/day) (365.25 day/yr) = $2.0490525/yr
Rounds to $2.05/yr

$7.45 as 0.00085*24*365