What do we need to pay attention to in the second year of junior high school? As the title suggests,

The second year of junior high school is very important. What others give you can only be an opinion. More importantly, it's yourself. I'm sure you can do it.

We need to pay attention to studying, but also to deal with interpersonal relationships, and so on.

Set A product x pieces, B product Y pieces, and 20X+35Y 800, and X 0, Y 7, the maximum profit is 10X+13Y. The orange object is drawn in the Cartesian coordinate system by the first three conditions, and find out the range with Wu Ming, and then draw the image of 0=10x+13y in the figure, translate, and see which point is farthest from 10x+13y=0 in the range found in front of the maximum point, and use the relationship between the lines to calculate it, and the final result is 5 pieces of product A and 20 pieces of product B. This is the method of high school.,I think this is the topic of the second year of junior high school.,I didn't think about it for a long time to argue to a better way to understand.,I'll provide this for your reference first.。。。

Solution: Let X pieces A y pieces B, and the profit is W

20x+35y=800

w=(30-20)x+(48-35)y=10x+13yy 7 synthesis, w= It can be seen that w decreases with the increase of y, so when y takes the minimum value of 7, w takes the maximum value as.

However, when y takes 7, x has no integer solution, that is, there is funds left; Therefore, when y takes 8, you can make full use of the funds, and at this time x=26

Profit w = 26 * 10 + 8 * 13 = 364

Let the profit be y, the quantity of commodity A is x1, and the quantity of B is x2:

Equation 1: y=(30-20)*x1+(48-35)*x2 (x2>=7).

10*x1+13*x2

Equation 2: 20*x1+35*x2<=800 (x2>=7) from Equation 1 to get x1=(y-13*x2) 10 Substituting into Equation 2 yields:

2*y+9*x2<=800 (x2>=7）y<= (x2>=7)

So when x2=7 there is a profit maximum: y=yuan).

Answer: A's profit margin is (30-20) divided by 20 is 50% B is (48-35) divided by 35 A's profit margin is high, so try to buy A If you only buy 7 pieces B, the remaining money can only buy 27 pieces A has 15 yuan left, so you should buy 8 pieces of B26 pieces A money is just 800 yuan, so the profit is the largest.

I think you're relying on our eyesight.

Add equation (1) x3 to equation (2) x4 to get x = 4 and substitut (1) to get y = 6