Current location - Training Enrollment Network - Mathematics courses - For solving math problems in the second volume of the seventh grade, as long as there are two difficult problems (solutions), it is best to solve them in a long process, please ask 3Q.
For solving math problems in the second volume of the seventh grade, as long as there are two difficult problems (solutions), it is best to solve them in a long process, please ask 3Q.
I have a few questions. Choose two questions by yourself. The latter two questions are longer than 1. A store's A-type clothing 100, each 50 yuan, B-type clothing 120, each 65 yuan; A clothing sold 80 pieces, B clothing sold 120 pieces, and two kinds of clothing * * * made a profit of 2760 yuan. Because of the seasonal changes, the store decided to discount the remaining two kinds of clothes at the cost price. If A's clothes are 30% off, how much discount should B's clothes be? Reference answer: The cost price of each piece of clothing B = {65 *120-[2760-80 * 50 * (1-0.7)]/120 = 52/65 = 0.8 in 52 yuan, so clothing B will be sold at a 20% discount. 2. The price tag is as follows: Number of ticket purchasers:1~ 5051~100100. Ticket price per person 13 yuan 1 1 Yuan 9 yuan. A shop needs to buy a batch of TV sets and washing machines. According to the survey, it is not less than half of the washing machine. The purchase price and selling price of the two electrical appliances are as follows: purchase price of TV sets and washing machines (RMB/set) 1800 1500 (RMB/set) 2000 1600 planned purchase 100 sets. At most, we can raise 16 1800 yuan (1) to figure out how many kinds of purchase plans there are (regardless of other expenses). (2) Find the most profitable plan: a store needs to buy a batch of TV sets and washing machines. According to the survey, it is not less than half of the washing machine. The purchase price and selling price of two kinds of electrical appliances are as follows: the purchase price of TV sets and washing machines (RMB/set)/KOOC-0/800/KOOC-0/500 (RMB/set) 2000/KOOC-0/600 * * Planned purchase/KOOC-0/00 sets, and the maximum fund can be raised/KOOC-0. From the meaning of the question: x ≥1/2 (100-x)1800x+1500 (100-x) ≤16/kloc-. 36, 37, 38, 39. Then 100-x = 66, 65, 64, 63, 62, 6 1 Answer: You can buy 34 televisions, 66 washing machines, 35 televisions, 65 washing machines, 36 televisions and 64 washing machines. 2) Find the most profitable scheme, because in 2000 >; 1600, so buy as many TV sets as possible. You should buy 39 TV sets and 6 1 washing machine. Profit: 39× 2000+6 1×1600 = 175600 (yuan) Answer: 39 TV sets and 61washing machine should be purchased, and the profit is175600 yuan. 4。 For any two numbers x and y, define a new "*". And X*Y=AX+BY+C solution: 3 * 5 = 3a+5b+c =154 * 7 = 4a+7b+c = 28 minus A+2B= 13 A= 13-2B into 3a+5b+.

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