Then 9 (x+2)+17x+14 (x-1) ≥ 200 ....................... ①.
9(x+2)+ 17x+ 14(x- 1)≤250.......................②
There are solutions of ①x≥4.9 and ②x≤6. 1, that is, 4.9≤x≤6. 1, and the unit price of prizes is required to be an integer.
So x=5.
A: The unit price of the first prize is 7 yuan, the second prize is 5 yuan, and the third prize is 4 yuan.