Now the ratio of salt to water is1:(4-1) =1:3.
Since water has not changed, the number of shares of water has also become the same, that is, 1: 4 = 3: 12.
1:3=4: 12
Have: original salt: present salt: water = 3: 4: 12.
Original brine: 16(4-3)×3×5 = 240(g)
2. Same as above: change the number of copies in the second group to the same number, that is, 2: 3 = 8: 12.
4:5= 12: 15
There are: first: second: third: = 8: 12: 15 (only when each ratio is equal can two ratios be combined into one ratio. ) Now the total number of people is 140, and then we can solve the problem according to the sum ratio.
3; Make sure that the total number of people has not changed, and make the total number of people in the two proportions the same.
Original one: Original two: Total number = 8: 7: (8+7) = 8: 7:15 = 24: 21:45.
Now 1: Now 2: Total = 4: 5: (4+5) = 4: 5: 9 = 20: 25: 45.
Yes: original population: 8÷(24-20)×24=48 (person)
Original number of two people: 8÷(24-20)×2 1=42 (person)
4. Storybook: Total = 2. 5 = 8.20 (same reason as above)
Science and technology books: storybooks = 7: 8
Storybook: Science Book: Literature Book: Total = 8: 7: (20-8-7): 20 = 8: 7: 5: 20.
Have: storybook: 144÷(8-5)×8=384 (this)
Science and Technology Book: 144÷(8-5)×7=336 (Ben)
Literary Books: 144(8-5)×5 = 240 (this edition)