Answer:
Fir tree = 9
Pine tree = 12
Explanation:
I'm assuming you need the height of the pine and fir tree.
Set the height of the pine tree to p and the height of the fir tree to f.
Now set up equations:
The combined height is 21 -
f + p = 21
4 fir trees is 24 taller than 1 pine tree -
4f = p + 24
Subtact 24 from both sides
4f - 24 = p
Now substitute 4f - 24 = p into the first equation
f + (4f - 24) = 21
SImplify:
f + 4f - 24 = 21
5f - 24 = 21
Add 24 on both sides
5f = 45
Divide by 5 on both sides
f = 9
The height of the fir tree is 9 meters.
Now put the 9 into the f + p = 21
f + p = 21
9 + p = 21
Subtract 9 on both sides
p = 12
The pine tree is 12 meters tall.