X-piece sportswear,
100 X = 10000+200× 10000/X
100x^2- 10000x-200× 10000=0
X^2- 100X-20000=0
(X-200)(X+ 100)=0
X=200 or-100 (truncated)
A: There are 200 sportswear in this batch.
(50 yuan
purchasing price
, selling 100 yuan)