Please make up a practical problem with the equation of half x plus three x plus four X

The school organizes donation activities for students in poverty-stricken areas. The activities are carried out for four days. The donations received on the second day are 1 / 2 of the first day, 1 / 3 of the first day on the third day, and 1 / 4 of the first day on the fourth day. According to the statistics, the total amount of donations received on the next three days is 50 yuan. How much is the donation received on the first day?

A formula of an applied problem
There are 8 cards for naughty. The small card is one sixth more than the naughty one. How many more cards is the small card? How many are the small cards?

Xiaoyou 8 + 8 * (1 / 6) = 28 / 3
A few more than naughty: 28 / 3-8 = 4 / 3

A clock is three minutes slow per hour. According to this calculation, after 5:00 in the morning is aligned with the standard time, when the clock points to 12:00 in the evening, the standard time is Time Points

When 12 + 12 = 24, set the standard time to pass x hours, then (5 + x-24) × 60-3x = 0, & nbsp; & nbsp; & nbsp; 60 (X-19) - 3x = 0, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 60x-1140-3x = 0, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp

A mathematical application problem of grade two in junior high school~~
It is known that the whole journey from Shanghai to Hangzhou is about 200 km. If the average speed of the bullet train is 0.5 km faster than that of the original express train per minute, it will take 20 minutes less than the original express train from Shanghai to Hangzhou. How many minutes does it take for the bullet train to arrive at Hangzhou Dayue from Shanghai?

It takes X minutes for a bullet train from Shanghai to Hangzhou
(200/x)-0.5=200/(x+20)
The solution is x = - 100 or x = 80
It takes 80 minutes for the bullet train from Shanghai to Hangzhou Dayue

21 is the smallest of several continuous odd numbers, and 32 is the largest of several continuous even numbers
The sum of them is 241. How many odd and even numbers are there?

Odd 5 21 + 23 + 25 + 27 + 29 even 4 32 + 30 + 28 + 26 suppose odd x, even 9-x. odd x, then from 21 to 21 + 2 (x-1) = 19 + 2x, even 9-x, then from 32 to 32-2 (8-x) = 16 + 2x, then there are: (21 + 19 + 2x) * x / 2 + (32 + 16 + 2x) * (9-x) / 2 = 241

21 is the smallest of several continuous odd numbers, 32 is the largest of several continuous even numbers. Nine odd and even numbers are known, and their sum is 241?

From the analysis, we know: 241 is odd, because odd + even = odd, so the odd number in the nine numbers is odd, and even is even. That is, there may be three or five odd numbers, 241 - (21 + 23 + 25) = 172172 is not a multiple of 6, 241 - (21 + 23 + 25 + 27 + 29) = 116116 is a multiple of 4, 32 + 30 + 28 + 26 = 116. Answer: there are five odd numbers and four even numbers

21 is the smallest of several continuous odd numbers, 32 is the largest of several continuous even numbers. Nine odd and even numbers are known, and their sum is 241?

From the analysis, we know that 241 is odd, because odd + even = odd, so the odd number in the nine numbers is odd, and even number is even. That is, there may be three or five odd numbers, 241 - (21 + 23 + 25) = 172172 is not a multiple of 6, 241 - (21 + 23 + 25 + 27 + 29) = 116116 is a multiple of 4, 32 + 30 + 28 + 26

21 is the smallest of several continuous odd numbers, 32 is the largest of several continuous even numbers. Nine odd and even numbers are known, and their sum is 241?

Five cards are marked with numbers 1, 2, 3, 4, 4 respectively. Two of them are randomly selected. The probability that the sum of the extracted numbers is even is calculated

Put it back, it's 13 out of 25

Please make up a practical problem with the equation of half x plus three x plus four X