"The capital invested by the school-run factory every day is not less than 5,560 yuan and not more than 2,600 yuan." I don't understand this. I don't know if it's the questioner's problem or what's going on. The game can't be played, and the data fights. ......

Regarding this problem, we might as well use the method of combining equations and inequalities to solve it, which may also be an important test point for the senior high school entrance examination.

Suppose A produces X sets every day and B produces Y pieces every day. According to the meaning of the question, x+y = 30,5560 < = 200x+180y < = 5600, which is available, 8 < = X < = 10. When X=8, Y = 22 when X=9, y = 21; When X= 10, Y=20.

To sum up, it is not difficult to see that there are three solutions to the problem 1.

For question 2, it is not difficult to figure out that as long as the selling price is subtracted from the cost, it is natural to know that the profit is big.

For question 3, we might as well calculate it according to 1 in three cases, and we will know it naturally.