4. In the reforestation action, the 4th-grade students planted 209 trees. Three times more oaks were planted than birches, 14 more maples than oaks, and as many poplars as half the number of planted birches. How many trees of each species were planted in this reforestation action?
First method:

The least number of poplars were planted, so let's denote the number of poplars planted in the reforestation action with $\mathrm{T}$.

$1 \text{ POINT}$

Since the number of poplars is half the number of birches planted, the number of birches planted is twice the number of poplars planted, i.e., the number of birches planted can be denoted as:

![](https://cdn.mathpix.com/cropped/2024_05_30_ba0648e72c3c0e2bc002g-2.jpg?height=80&width=169&top_left_y=1214&top_left_x=869)

$1 \text{ POINT}$

The number of oaks is three times the number of birches, so the number of oaks can be denoted as:

![](https://cdn.mathpix.com/cropped/2024_05_30_ba0648e72c3c0e2bc002g-2.jpg?height=74&width=503&top_left_y=1351&top_left_x=705)

$1 \text{ POINT}$

Since 14 more maples were planted than oaks, their number can be denoted as:

| $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | 14 |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- |

$1 \text{ POINT}$

The total number of 209 planted trees can be represented as:

| $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | $\mathrm{T}$ | 14 |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 1 | $1 \text{ POINT}$ |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

Since $209-14=195$, and $195: 15=13$, we conclude that the number of poplars planted is 13. 2 POINTS Finally, the number of birches planted is $2 \cdot 13=26$, oaks $3 \cdot 26=78$, and maples $78+14=92$. 3 POINTS TOTAL 10 POINTS