1, solution: Let the amount of price increase above 50 be X yuan, and get the following equation:

(50-40+X)×(500- 10X)=8000

x = 10； Then, the goods with the unit price of 40 yuan were sold in 60 yuan, and the number of goods sold was 400, with a profit of 8,000 yuan.

There are also 200 purchases. According to each purchase in 80 yuan, the profit is also 8,000 yuan. 2. Suppose the price rises by X yuan, then the profit is 10+X yuan, and the sales volume is 500-10+X.

So the profit is (x+ 10) (500- 10x).

=- 10x square +400X+5000

The symmetry axis is X = 20, so when X = 20 yuan, the profit is the largest, and the selling price is 50+20 = 70 yuan. Besides, I tell you, no one can do everything. That only means that others have done more and learned more than you. I've been doing it for a long time. I have to think hard. )