A sixth grade arithmetic problem Party A and Party B set out from two places and walked towards each other. After meeting, it took 18 minutes for Party A to continue to walk the whole journey, and it took 8 minutes for Party B to walk the rest of the journey. When did Party A and Party B meet? Notice that it took a 18 minute walk to finish the rest of the journey

A sixth grade arithmetic problem Party A and Party B set out from two places and walked towards each other. After meeting, it took 18 minutes for Party A to continue to walk the whole journey, and it took 8 minutes for Party B to walk the rest of the journey. When did Party A and Party B meet? Notice that it took a 18 minute walk to finish the rest of the journey

A speed x, B speed y, encounter time t
xt=8y 1
yt=18x 2
18xx = 8yy
So x / y = 2 / 3
T = 12 minutes

It is required to have the formula of integer, decimal, fraction, addition, subtraction, multiplication and division (must have). The more the better, and there is no top,

Basically, all of them can be calculated simply. Some problems need to be solved by yourself. 2.5 × 80% + 2.5 × 20% 125 × 3 / 2 × 0.86.05 △ 3.025-20 × 1% 5.3 △ 5.3% × 0.53180.7 × 56.7 △ 5.673.83 △ 1.915 + 5 / 3 600 × 3 / 20 × 20 / 3 230.1 △ 65 × 13 / 25 (6.08-3.26) △ 3 / 50.8 × 100

For a bookshelf, the ratio of the number of books on the upper shelf to that on the lower shelf was 5:6. Later, 30 books from the upper shelf were put on the lower shelf. Later, the ratio of books on the upper shelf to that on the lower shelf was 3:4. How many books were there on the upper shelf and the lower shelf?

The total number of books is constant, set to 1
It turns out that the upper level accounts for the total number of:
5/(5+6)=5/11
After taking out 30 copies, the upper level accounted for the total number of:
3/(3+4)=3/7
Reduced:
5/11-3/7=2/77
The total number is:
30 △ 2 / 77 = 1155 copies
original,
Upper layer: 1155 × 5 / 11 = 525
The lower layer has: 1155-525 = 630 copies