(2) If the selling price is X yuan, the price will be reduced to (260-x).
So the sales volume increased by (260-x) tons, and the quantity sold was x[(260-x)+40].
The monthly profit is (x-100) [40+(260-x)] =10000.
Finishing (x-200)2=0
The result is x=200.
Answer: (1) At this time, the sales volume is 60 tons; (2) The price per ton is 200 yuan.