Answer: 47.5% of the trees are elm trees.
Step-by-step explanation: To find the percentage of elm trees out of a total of 40 trees, we can follow these steps:
1. Identify the number of elm trees, which is given as 19.
2. Divide the number of elm trees by the total number of trees, which is 40.
19 / 40 = 0.475
3. Multiply the result by 100 to convert it to a percentage.
0.475 * 100 = 47.5%
Therefore, 47.5% of the trees are elm trees.