One-time processing capacity: -20%-X+50.
Processing capacity of B:1/3 ~ x-20% x-50 ~-300 =1/3 ~ 80% x-50 ~-300 = ~ 4/661.
The sum of the quantities processed by Party A and Party B: (20%) x+50+4/15) x-850/3 = (7/15) x-700/.
Processing capacity of C: 3/4 [x-7/15x-700/3]+25 =-2/5-x+200.
∴[﹙7/ 15﹚x-700/3]+[﹙2/5﹚x+200]+ 1300=x
﹙ 13/ 15﹚x- 100/3+ 1300=x
2/ 15x=3800/3
x=9500
This shipment has 9500 parts.