Mr. Zhang bought 30 kg of apples and peaches (unit price: 8 yuan for apples and 5 yuan for peaches) and paid 216 yuan in total. How many jin of apples and peaches did he buy

30*8=240 8-5=3 240-216=24 24/3=8 30-8=24
Peaches 8 kg, apples 24 kg, this problem can be calculated with chicken and rabbit in the same cage

Mr. Li bought three kilograms of apples and one kilogram of peaches for a total of 50 yuan. If the apples cost n yuan per kilogram, how much is a kilogram of peaches?

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Mr. Li spent 29.6 yuan to buy 4 kg of oranges and 2 kg of apples. The money for 1 kg of apples can buy 2 kg of oranges, and how many apples and pears per kg

If the price of orange is x, the price of apple is 2x
4x+ 2x×2=29.6
x=3.7
2x=7.4
A: the price of apples is 7.4 yuan / kg, and that of oranges is 3.7 yuan / kg

Xiao Ming read a book. On the first day, he read more than 16 pages of the book. On the second day, he read less than 2 pages of the book. There are 88 pages left. How many pages are there in this book?

Let this book have X pages & nbsp; & nbsp; & nbsp; & nbsp; X = 18x + 16 + 16x-2 + 88 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 724x + 102 & nbsp; x-724x = 724x + 102-724x & nbsp; & nbsp; & nbsp; 1724x = 1021724x △ 1724 = 102 △ 1724 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 144 A: this book has 144 pages

The known set M = {x | m + 1 / 6, m belongs to Z}, n=

Because m + 1 / 6 = (6m + 1) / 6,
n/2-1/3=(3n-2)/6 ,
p/2+1/6=(3p+1)/6 ,
And 6m + 1 = 3 * (2m) + 1, 3n-2 = 3 (n-1) + 1,
So n = P, M is a subset of n (and of course a subset of P)

The speed ratio of passenger and freight cars is known to be 4:5. After the two cars meet on the way, they continue to drive. The passenger car increases the speed by 20%, and the freight car keeps the same speed. After another four hours, the freight car arrives at a, and the passenger car is 116 kilometers away from B. how many kilometers are there between a and B?

If the speed of freight car is 44 + 5 △ 4 = 19 after meeting, the speed of passenger car before 20% increase is 19 × 45 = 445; if the speed of passenger car after 20% increase is 445 × (1 + 20%) = 875; if the speed of passenger car is 875 × 4 = 3275 after meeting, the distance between passenger car and ground B is 59-3275 = 29225, the distance between two places is 116 △ 2922

Given that the difference between the quadratic power of the polynomial 2x + my-12 and the quadratic power of the polynomial NX - 3Y + 6 does not contain x, y terms, find the value of M + N + Mn

2X ^ 2 + my-12 - (NX ^ 2-3y + 6) = (2-N) x ^ 2 + (M + 3) y-18 does not contain x, and y has 2-N = 0, M + 3 = 0
===> n=2,m=-3
===>m+n+mn=-3+2-6=-7

Dad takes Beibei to school by bike, 420 meters per minute. After school, he walks home by himself, 80 meters per minute. Cycling takes 34 minutes less than walking. How many meters is it from Beibei's home to school?

With X meters, then
x/420 +34 = x/80
The solution is x = 3360m

With unknowns______ It's an equation

An equation with unknowns is an equation, so the answer is: an equation

2. As for the rocket, the correct thing is that a flies by the reaction force of air, B can fly in the space without air, and C can fly with the jet engine of the plane

This question should be a
But the C answer doesn't seem to be finished, does it?
Now let me explain why a and B should be chosen
A: The forces are mutual. If the jet jet gives the air a backward force, then the air will also give the engine a forward force, which is a reaction force. Therefore, the jet drives the whole aircraft to move. Option a is correct
B: In space, we generally regard it as a vacuum, mainly because there is no air in space. (first of all, it is generally not a plane but a satellite that operates in space.) how does a satellite operate without the reaction of air to the aircraft? This is because the satellite has an initial velocity, and the earth provides a centripetal force to the gravity of the satellite. Centripetal force is an effect, The faster the speed is, the farther the distance from the earth is. (I recommend you ask your teacher about this knowledge point, or read the textbook in the online bookstore. It's very difficult for me to explain it clearly just by mouth, mainly because I don't know if you have learned this knowledge point of circular motion.)
I hope my answer can help you

Mr. Zhang bought 30 kg of apples and peaches (unit price: 8 yuan for apples and 5 yuan for peaches) and paid 216 yuan in total. How many jin of apples and peaches did he buy