X+Y= 16
4800 * X/60+ 12000 * Y/60 = 1880
Solution: X= 1 1.
Y=5
It took 1 1 minute to go uphill and 5 minutes to go downhill, making a total of 16 minutes.
Suppose there are x pigeons on the tree and y pigeons under the tree.
Then all pigeons are (x+y)
(y- 1)/(x+y)= 1/3①
x- 1=y+ 1②
② Simplify to get x=y+2.
Substitute x=y+2 into ①.
The solution is y=5.
∴x=7
There are 7 pigeons in the tree and 5 pigeons under the tree.