Second, in any case, you can't lose a cake in five minutes, so the number of times is the main one, and the shortest one is four, so it takes at least 20 minutes.
3. Let an action number x 14x+6= 19x-4 x=2, then the class number is 14x2+6=34.
Fourth, the whole family is 73 years old. Four years ago, at the age of 58. It is reasonable to say that she should be 57 years old four years ago, so there is only one answer. Her brother was not born four years ago. He was born in 1 year. So it is concluded that his brother is 3 years old and his sister is 5 years old, so the sum of his parents is 73-5-3=65 years old. Father is 3 years older than mother, biological father is 34 years old, and mother is 365,438+0 years old. The answer is: brother: 3 sisters: 5 fathers: 34 mothers: 365,438+0.
Because it is a square, its length is equal to its width. If x is taken, then x+x- 1=23 (one person coincides), and the solution is x= 12. So the total number of people is 12x 12= 144, and 23 people are reduced to 1265438.
6. Let the unit price of football be X and basketball be y 5x+4y=400 2x+3y=2 16. Solve this equation set X=48 Y=40, football 48, basketball 40 yuan.
Seven, two rows of 20 cars, a row of 10 cars are 8 meters apart, so the first car head to the last car tail is 5x 10+8x9= 122.
So the total length of crossing the bridge is 478+ 122=600 meters per minute, so it takes 6 minutes.
Answer finished: