Suppose the first one is X, then the second one is x-52, and x+x-52=-42, then x=5.
The first number is 5, and the second number is -47.
Support that the first number is X, then the second number is x-52.
x+x-52=42
x=5
So, the first number is 5 and the second number is -47.
3. The difference between two numbers is 16, three times of a large number is equal to nine times of a decimal, and these two numbers are balls.
Suppose that the large number is x, the decimal number is x- 16, 3x=9(x- 16) and x=24, then the large number is 24 and the decimal number is 8.
Assuming that the larger number is X, the smaller number is x- 16.
3x=9(x- 16)
X=24, then x- 16=8.
Therefore, the larger number is 24 and the smaller number is 8.
5. Soybean meal contains protein 16%, and corn meal contains protein 9%. How many pounds do you need to mix to get 350 pounds of mixture containing 12% protein?
Suppose that soybean meal needs x pounds, and corn flour needs 350-x pounds,16% x+9% (350-x) =12% times 350, and x= 150.
Suppose soybean meal is x pounds, then corn meal is 350-x pounds.
16% x+9% (350-x) =12% times 350.
x= 150，350-x=200
Therefore, soybean meal needs 150 pounds, and corn meal needs 200 pounds.
7. One beverage contains 15% orange juice and the other contains 5% orange juice. How many liters do these two drinks need to be mixed to get a 10L drink containing 10% orange juice?
Suppose that the first one has X liters, the second one has 10-x liters,15% x+5% (10-x) =10% times10, and x=5.
Suppose the former is x liters, then the latter is 10-x liters.
15% x+5% (10-x) =10% times10.
x=5， 10-x=5
Therefore, the former needs 5L, and the latter also needs 5L.
They are all solved according to the equation model that foreigners like.