An eight-month used stereo system was sold for $255.75. This was one third (1/3) the amount of what this system originally cost. What was the original cost of this set?

From the givens, we know that 1/3 of the original cost is $255.75

Assume that the original price of the stereo is y, therefore:

(1/3) y = 255.75

y = 3 x 255.75

The original price of the stereo is $767.25