He got 250 * .8 = $200. He gets a 600 * .25 = $150 discount on the second system. So it cost 600 - 150 = $450. So he was 450 - 200 = $250 out of pocket.
This justifies what answer for what question? Q & A:
John decides to trade in his stereo system. His old system cost 250 dollars and he got 80% of the value for it. He then buys a system that costs $600 that he gets a 25% discount on. How much money came out of his pocket?
250