The specific explanation of Dingdang is as follows:
Draw two quantities in a picture, mark the unit "1", and mark the known quantity with two marks, which is helpful for analysis.
Step 1: Read the sentences about fractions and know which quantity accounts for a fraction of which quantity. Draw them first, and then determine which of the two quantities is the unit "1".
Step 2: Look at another condition in the topic, which quantity is known, and mark it under the corresponding quantity to determine the method.
Known quantity is nothing more than the following situations:
1, known unit "1", multiplication rate, corresponding quantity.
If the quantity of the unit "1" is known, that is, what is the fraction of this number, the multiplication formula is listed directly and the quantity corresponding to this fraction is found.
2. When the corresponding quantity is known, divide by the fraction to get the unit "1".
If the quantity corresponding to the fraction is known, that is, what fraction of the unit "1" is known, find the quantity of the unit "1".
3. Given the sum of two quantities, the unit of equation addition and solution is "1".
If the sum of these two quantities is known, it means that these two quantities are unknown and suitable for solving equations. Let the quantity with the unit of "1" be X, and list the addition equation according to the equivalence relation of the sum of the two quantities, and the unknown quantity obtained is the quantity with the unit of "1".
4. Given the difference between two quantities, subtract the equation, and the unit of the solution is "1".
If the difference between these two quantities is known, it means that these two quantities are unknown and suitable for solving equations. Let the quantity with the unit of "1" be X, and list the subtraction equation according to the equivalence relation of the difference between the two quantities, and the unknown number obtained is the quantity with the unit of "1".