Math problem (with answer) in the second volume of the first day of junior high school. Thank you!
1. In order to save energy, a unit charges electricity according to the following regulations every month: the electricity consumption does not exceed 140 kwh, and it is charged at 0.43 yuan per kwh; If it exceeds 140 degrees, the excess will be charged at 0.57 yuan per degree. If the average electricity bill charged by Mexican consumers in April is 0.5 yuan per kWh, how much should consumers pay in April? Let the total power consumption be x degrees: [(x-140) * 0.57+140 * 0.43]/x = 0.50.57x-79.8+60.2 = 0.5x0.07x =19.6x = 0.57 = 79.8 79.8+60.2 =140 2.1) The ratio of delivery staff to sales staff in the home appliance department of a shopping mall is 1: 8. Due to the obvious increase in the purchase of home appliances this summer, the manager of the home appliance department transferred 22 people from the sales staff to deliver the goods. Results The ratio of delivery staff to sales staff was 2: 5. How many delivery staff and sales staff are there in the home appliance department of this shopping mall? Suppose there are x delivery people and 8X sales people. (x+22)/(8x-22) = 2/55 * (x+22) = 2 * (8x-22) 5x+1/kloc-0 =16x-441/kloc. Suppose: increase X% 90% * (1+X%) = 1 solution: X = 1/9 Therefore, the sales volume is increased by11%compared with the original price. After the price of commodity B is increased by 5%, the sum of the unit prices of the two commodities is increased by 2% compared with the original sum of the unit prices. What is the original unit price of commodity A and commodity B/Let the original unit price of commodity A be X yuan, then B is100-x (1-10%) x+(1+5%) (100-x). Find the original number of people in each workshop. Assuming that there are X people in workshop B, the equation is listed as follows: X+4/5x-30 = X-10+3/4 (X-10) X = 250, then the number of people in workshop A is 250 * 4/5-30 =/kloc-. B rides a bike from B to A, and both of them advance at a constant speed. You should know that at 8 o'clock in the morning, at the same time, the difference between 10 in the morning and 12 at noon is 36 kilometers. How to find the distance between a and b? (Equation) Let the distance between A and B be x x-(x/4) = x-72 x = 288a: The distance between A and B is 288 6..A The length of A and B cars is180m. If two trains are running opposite each other, it takes *** 12 seconds to leave from the front to the rear. If driving in the same direction, it takes 60 seconds from the front of car A to the rear of car B, and the speed remains unchanged. Find the speed of a car and b car. The sum of the speeds of the two vehicles is [180 * 2]/12 = 30m/sec. If the speed of A is x, then the speed of B is 30-x180 * 2 = 60 [x-(30-x)] x =18, that is, A. coarse firing lasts 3 hours and fine firing lasts 8/3 hours. When the power went out, two candles were lit at the same time, and when the phone came in, they were blown out at the same time. The thick one is twice as long as the thin one, and the power outage time is calculated. Let the total length of power outage be x, and the unit is 1, so the coarse burning is 1/3 and the fine burning is 3/8 1-x/. 4 is the power failure. Four hours. 1. A group plans to make a batch of "Chinese knots". If everyone does five, it will be nine more than planned. If everyone does four, it will be less than planned 15. How many team members are there? How many Chinese knots do they plan to make? There are x members in the group, 5x = 4x+15+95x-4x =15+98. A middle school organizes a spring outing for junior one students. It was originally planned to rent a number of 45-seat buses, but 15 people had no seats. If you rent the same number of 60-seat buses and have one more, the rest will be just full. (1) What is the number of students in Grade One? How many 45-seat buses were originally planned to be rented? Solution: rent 45 buses x, rent 60 buses (x- 1), 45x+ 15=60(x- 1) solution: x=5 45x+ 15=240 (person) answer: one. The plan to rent a 45-seat bus is too much and too limited for five answers. This is the address. /question/85 187559 . html/question/8220 142 . html? fr=qrl&。 Fr2 = The query can find so much,