Answer:
There are 16 Oak tree in the forest.
Step-by-step explanation:
Given: There are 4 Oak tree on every 10 pine trees.
There are total 24 more pine tree than Oak tree.
Using the ratio of trees to find the number of trees.
Lets assume there are total number of Oak tree be "x".
∴ Total number of Pine trees will be 
We know the ratio of Oak to Pine tree is 4:10 or 
⇒
Multiplying both side by 
⇒ 
Using distributive property of multiplication, distributing 4 with x and 24.
⇒ 
Multiplying both side by 10
⇒ 
subtracting both side by 4x
⇒ 
dividing both side by 6
⇒
∴ 
Hence, There are 16 Oak trees in the forest.
Ten thousand - 10,000
thousand literally just haves 1,000
if the twenty is before the three zeros, it would be 20,000 which is twenty thousand. its the same with other numbers. its super simple!
It's a bit hard to explain but I hope this helps