In order to promote a commodity with the same price, supermarket a, supermarket B and supermarket C cut prices by 20% twice in a row, 40% at a time in supermarket B, 30% at the first time in supermarket C and 10% at the second time. Which supermarket is more cost-effective for customers to buy this commodity A. B. B. C. C. D

In order to promote a commodity with the same price, supermarket a, supermarket B and supermarket C cut prices by 20% twice in a row, 40% at a time in supermarket B, 30% at the first time in supermarket C and 10% at the second time. Which supermarket is more cost-effective for customers to buy this commodity A. B. B. C. C. D

According to the meaning of the question: A, 80% × 80% = 64% B, 60% C, 70% × 90% = 63% B. It's more cost-effective for supermarkets to buy this kind of goods

The stationery counter of a shopping mall bought a batch of pens at the price of a (a is an integer) yuan, and decided to increase the price of each pen by 2 yuan,
=(339a+678+127)/(a+2)
=[339(a+2)+127]/(a+2)
=339+127/(a+2)
These three steps are how to become, thank you, tonight to ~ good plus 50 points!

Your first step = (339a + 678 + 127) / (a + 2)
Step 2: take (339a + 678) as a whole. Extract the common factor 339, so the result is 339 (a + 2)
Step 3: according to the fraction operation, it becomes 339 (a + 2) / (a + 2) + 127 / (a + 2)
That's the last cut

As shown in the figure, in the rectangle ABCD, BC = 2, DC = 4, the semicircle o with ab as the diameter is tangent to DC at e, then the area of the shadow part is______ (the results are expressed by exact values)

If AB is taken as the diameter, OA = ob = 12CD = 2, the area of semicircle is 12 × π × 22 = 2 π, the area of rectangle ABCD is 2 × 4 = 8, so the area of shadow is 8-2 π

Given that m and N are opposite numbers and satisfy (M + 4) &# 178; - (n + 4) &# 178; + 16, find the value of M & # 178; + n & # 178; - 2Mn

The problem should be to know that m and N are opposite numbers, and satisfy (M + 4) &# 178; - (n + 4) &# 178; + 16 = 0, find the value of M & # 178; + n & # 178; - 2Mn, and know that m and N are opposite numbers, M + n = 0 (M + 4) &# 178; - (n + 4) &# 178; + 16 = 0m & # 178; + 8m + 16-n & # 178; - 8n-16 + 16 = 0m & # 178; - N & # 178; + 8m-8n + 16 = 0 (...)

Primary school mathematics on off form calculation from what? Second grade or third grade

In the textbook, we only learn in the third grade, but when we do extracurricular exercises, there are many teachers in the second grade who will teach in the second grade
It's usually for two years
14 + 3 + 7 = 24
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seventeen
In this way,

1. The perimeter of a rectangle is 180cm, and its width is 4 / 5 of its length. What is the area of the rectangle?
2. The total weight of two bags of rice is 180 kg. If 1 / 63 is taken from bag a and put into bag B, how many kg are the two bags of rice?

1. The circumference of a rectangle is 180 cm, and the width is 4 / 5 of the length. What is the area of the rectangle? Length = 180 △ 2 × 1 △ 1 + 4 / 5 = 50 cm; width = 50 × 4 / 5 = 40 cm; area = 50 × 40 = 2000 square cm; 2. Two bags of rice weigh 180 kg in total. If 1 / 63 is taken out of bag a and put into bag B, two bags of rice will each

How to calculate the fifth power of a plus B
The fifth power of a plus B bracket!

a^5+5a^4b + 10a^3b^2+10a^2b^3+5ab^4+b^5
Take a look at the Yanghui triangle

It took 24 seconds for a train to cross the 360 meter long railway bridge, and 16 seconds for a train to cross the 216 meter long railway bridge at the same speed______ Rice

Speed: (360-216) / (24-16) = 144 / 8 = 18 (m), train length: 18 × 24-360 = 72 (m), or 18 × 16-216 = 72 (m). Answer: this train is 72 m long

As shown in the figure, in the trapezoidal ABCD, AD / / BC, e is the midpoint of AB, CE exactly bisects the angle BCD, proving that CD = AD + BC

Make ef / / BC through point E and make CD at point F
∵ e is the midpoint of AB, and EF / / BC
∴EF＝1/2（AD+BC） FC=1/2CD
∵EF//BC
∴∠FEC=∠BCE
∵∠BCE＝∠FCE
∴∠FEC=FCE
∴EF=FC
∵FC=1/2CD
∴EF=1/2CD
∴CD=AD+BC

The speed of light in vacuum is 300000 kilometers per second. "Light year" is a unit to measure the distance of celestial bodies. It refers to the distance light travels in a year
How many thousands of kilometers is a light year
What's the formula

1 year = 365 days = 365 × 24 hours = 365 × 24 × 60 minutes = 365 × 24 × 60 seconds = 3153600 seconds
So 1 light year = 30 × 3153600 = 946080 million km