Roi is 40 years old with his mother, who is four times as old as Roi. How old are Roi and his mother?
We take the age of Roi as 1 times. Mom is four times the age of Roi? In this way, the sum of the age of Roi and his mother is equivalent to the age of Roi. Five times are 40 years old, that is, (4+ 1) times. It can also be understood as five copies of 40 years old. So how much is 1 time, and how much is 4 times?
The sum of (1)Roi and his mother's age multiple is: 4+ 1=5 (times).
(2) Age of ROI: 40? 5 years old =8 years old
(3) Mother's age: 8? 4=32 years old
Comprehensive: 40? (4+ 1)=8 years old 8? 4=32 years old
To ensure the correctness of this question, please verify that
(1)8+32=40 years old (2)32? 8=4 (times)
The calculation results meet the requirements, so the problem is correct.
Two planes A and B fly in opposite directions from the airport at the same time, flying 3600 kilometers in three hours. The speed of A is twice that of B. What are their speeds?
Knowing that two planes fly a total of 3600 kilometers in three hours, we can find out the distance that two planes fly every hour, that is, the sum of the speeds of the two planes. This speed sum is equivalent to three times the speed of aircraft B, so that the speed of aircraft B can be calculated, and then the speed of aircraft A can be calculated according to the speed of aircraft B. ..
Planes A and B are traveling at speeds of 800 kilometers and 400 kilometers per hour respectively.
3. My brother has 20 extracurricular books and my brother has 25 extracurricular books. How many extra-curricular books did my brother give him? His extra-curricular books are twice as many as his brother's?
Thinking: (1) What is the same number of topics before and after my brother gives my brother extra-curricular books?
(2) What conditions do I need to know if I want to ask my brother how many extracurricular books to give my brother?
(3) If the extracurricular books left by my brother are regarded as 1 time, how many times can my brother's extracurricular books be regarded as the extracurricular books left by my brother?
On the basis of thinking about the above problems, ask my brother how many extracurricular books he should give his brother. First check how many extracurricular books my brother has left according to the conditions. If we regard my brother's extracurricular books as 1 time, then my brother's extracurricular books can be regarded as twice as much as his brother's extracurricular books, that is to say, the two brothers share three times as much as their brother's extracurricular books, and the total number of extracurricular books of the two brothers is always the same.
(1) The number of extracurricular books shared by two brothers is 20+25=45.
(2) After the elder brother gave his younger brother several extracurricular books, the two brothers took a multiple of 2+ 1=3.
(3) The number of extracurricular books left by my brother is 45? 3= 15。
(4) The number of extracurricular books given by elder brother to younger brother is 25- 15= 10.
Try to list the comprehensive formulas:
4. Two grain depots, A and B, originally coexisted with 170 tons of grain, but later A shipped out 30 tons and B shipped out 10 tons. At this time, A's stock grain was twice that of B. How many tons were originally stored in these two grain depots?
According to the original co-existing grain 170 tons of the two grain depots A and B, how many tons of co-existing grain are there in the two warehouses A and B when 30 tons are shipped from warehouse A and 10 tons are brought in from warehouse B? According to? At this time, A has twice as much grain in stock as B? If the grain in stock of B is 1 times at this time, the grain in stock of A and B is equivalent to 3 times that of B. So find out how many tons of grain in stock of B at this time, and then find out how many tons of grain in stock of B.. Finally, we can find out how many tons of grain warehouse A originally stored.
Warehouse A originally stored 130 tons of grain, and warehouse B originally stored 40 tons of grain.