1, 12m is cut from the first rope, and 14m is connected to the second rope. At this time, the length of the second rope is three times that of the first rope, so14+12 = 25m is twice that of the first rope at this time.
The original length of the two ropes = (12+14)/2+12 = 25m.
2. 2360/7-80 = 257. 14m/ min
3.x years ago
4 1 x = 4( 14 x)
x=5
Dad was four times as old as Xiaohong five years ago.
The son is three times as old as his father and eight years older than his father. Then the age of father and son and +8 years old are exactly four times that of son.
Therefore, the age of the son =(64+8)/4= 18 years old.
Father's age =64- 18=46 years old.
5. When the upper bottom is extended by 6 cm, it becomes a parallelogram, that is, the lower bottom is 6 cm longer than the upper bottom.
The trapezoidal bottom is twice as large as the upper bottom, so the upper bottom is 6, and the lower bottom =6*2= 12.
6. The bottom is twice that of the upper bottom, and the upper bottom is equal to the waist, so the circumference of the whole isosceles trapezoid =5* the length of the upper bottom.
So the upper sole = waist =25/5=5cm.
Bottom =5*2= 10cm
7. After adding a 0 at the end of a number, it becomes 10 times of the original number, which is 9 times larger.
The number obtained is 36 more than the original number.
Therefore, the original number =36/9=4.
8. (6+4) * 60/2 = 300m
9. Distance difference = 20m, speed difference = 7-5 = 2m/s..
Pursuit time =20/2= 10 second
The weight of 10 and 13 glasses of water = 8 10- 160 = 650g (the bottle weight is just the same).
A glass of water = 650/ 13 = 50g.
Bottle weight = 160-50 * 3 = 10g.