Students went to plant trees. The first group planted 18 trees in 30 minutes, and the second group planted 12 trees in 18 minutes. Which group planted trees faster?
Group 1: 18 trees / 30 minutes = 3 / 5 trees / minute
The second group: 12 (trees) / 18 (minutes) = 2 / 3 (trees / minutes)
The first group: 3 / 5 = 9 / 15
Group 2: 2 / 3 = 10 / 15
By comparison, the second group is faster
There are 356 trees planted on one side of one kilometer. Every two trees are 10 meters apart. How long is the highway?
(356-1) * 10 = 3550m
Because every two trees are 10 meters apart, there are 355 sections
Let's take a simple example: if you draw 4 trees, do you have 3 spaces, 5 trees have 4 spaces, and so on, so 356 trees have 355 spaces. Think about it carefully!
Three tree planting teams planted 1900 trees. Team a planted twice as many trees as team B. Team B planted 300 fewer trees than team C. how many trees did each of the three teams plant?
Team B planted x, then a is 2x, and C is x + 300
2x+x+x+300=1900
4x=1600
x=400
A: a 800 B 400 C 700