60% off. Suppose it was M yuan, the original sales volume was Y, the original sales volume was mine, the discounted sales volume was 1/2Y, and the discounted sales volume was 1/5MY.
Suppose it is x-folded. The discount price is XM.
So there is: XM* 1/2Y= 1/5MY, so1/2x =1/5x = 2/5 = 40%.