The cost of dvd players has dropped by $20 each year. if a dvd player cost $189 four years ago, how much does it cost today

It costs $189-(4×$20) which is $189-$80=$109

Ifound this on google “that means that the graph of a function with direct variation has these features: it is a straight line: because the slope is the ratio y/x = k. it passes through the origin (0,0): because y = kx = k (0) = 0.” i hope this you for what your looking for