A person's salary is 240 yuan. There are 50 pieces of 2 yuan, 5 yuan and 10 yuan, of which 2 yuan and 5 yuan are the same number. There are () pieces of 10 yuan This is one of the winter vacation assignments in the first semester of grade six

A person's salary is 240 yuan. There are 50 pieces of 2 yuan, 5 yuan and 10 yuan, of which 2 yuan and 5 yuan are the same number. There are () pieces of 10 yuan This is one of the winter vacation assignments in the first semester of grade six

X for 2 and 5, y for 10
2X+Y=50
7X+10Y=240
We get x = 20, y = 10
So there are 10 tickets for 10 yuan!

Uncle Zhang gets 305 yuan of salary, including 50 pieces of 2 yuan, 5 yuan and 10 yuan, of which 2 yuan and 5 yuan are the same number. How many pieces are 10 yuan

Youyou, President system,
Suppose that the total amount is 10 yuan
50 × 10 = 500 yuan
More:
500-305 = 195 yuan
2 yuan and 5 yuan in total:
195 △ 10 - (2 + 5) △ 2] = 30 (sheets)
10 yuan are:
50-30 = 20 yuan

In a donation activity, class 6 (1) donated 240 yuan in total, including 50 pieces of RMB of 2 yuan, 5 yuan and 10 yuan, of which 2 yuan and 5 yuan are the same number, so how many pieces of RMB of 10 yuan?

Let 2 yuan and 5 yuan each be x, then 10 yuan RMB is (50-2x), 2x + 5x + 10 (50-2x) = 240 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 13X = 260 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 2050-2x = 50-2 × 20 = 10 (sheets) a: there are 10 yuan RMB

A person gets 240 yuan, including 50 pieces of 2 yuan, 5 yuan and 10 yuan, of which 2 yuan and 5 yuan are the same number, so what is 10 yuan?

Let 2 yuan and 5 yuan have X pieces, then 10 yuan has 50-2x pieces,
（2+5）x + 10（50-2x）=240
The solution is x = 20
So 10 yuan has 50-20-20 = 10
Arithmetical solution: 2 and 5 as many as 7
Then 2 yuan is (50 × 10-240) / (10 × 2-2-5) = 20 pieces
So there are 50-20-20 for 10 yuan

If the average of 2,3,5 and X is 7, and the average of X, y, 3 and 6 is 8, try to find the value of X and Y. (write the process)

2+3+5+x=4*7=28
x=18
18+y+3+6=4*8=32
y=5

Party A and Party B set out from ab at the same time and travel in opposite directions. Party A travels 48 hours per hour and Party B 42 kilometers per hour. The two cars meet at 18 kilometers from the midpoint. How far is the distance between AB and Party B?

2*18÷（48-42）=6
6*（48+42）=540km

Prove by mathematical induction: 12 × 4 + 14 × 6 + 16 × 8 + +12n (2n + 2) = N4 (n + 1) (where n ∈ n *)

It is proved that: (1) when n = 1, the left side of the equation = 12 × 4 = 18, and the right side of the equation = 14 (1 + 1) = 18, the equation holds. (2) suppose n = K (K ≥ 1. K ∈ n *), that is, 12 × 4 + 14 × 6 + 16 × 8 + + 12K (2k + 2) = K4 (K + 1), then when n = K + 1, 12 × 4 + 14 × 6 + 16 × 8 + + 12K (2k + 2) + 1

On the map with a scale of 1:3000000, the distance between a and B is 3cm, so the actual distance between a and B is ()

If the actual distance between a and B is x cm, then
1:3000000=3:x
The solution is x = 9000000 (CM) = 90 (km)
Therefore, the actual distance between a and B is (90 km)
The answer is over

If y is a positive number, 2x + 3Y = 7, then the minimum value of 3 / x + 5 / y is

Multiply the two formulas to get 21 + 9y / x + 10x / y = 7 (3 / x + 5 / y)
The formula on the left > = 6 root sign 10
So (3 / x + 5 / y) > = 6 radical 10 / 7
The minimum value is 6 root sign 10 / 7, if and only if 9y / x = 10x / y, 2x + 3Y = 7

Three fifths of number a is equal to two thirds of number B (number a and number B ≠ 0). The difference between number a and number B is 10. Number a is () and number B is ()

Let a be x and B be y
Then: 3 / 5x = 2 / 3Y
By analyzing the meaning of the title, we can see that x > y
Then: X-Y = 10
Combining ① and ② into a set of equations, the following results are obtained
3/5x=2/3y
x-y=10
The results are as follows
x=100
y=90