4(2x-5)+7(x+2)
bracket means multiplying
do 4(2x+5) first
4*2x=8x
4*-5=-20
7*x=7x
7*2=14
8x-20+7x+14
do the x first
8x+7x=15x
-20+14=-6
answers: 15x-6 or -6+15x
Answer: The height of each fir tree is 9 meters, and the height of each pine tree is 12 meters.
Step-by-step explanation:
Let x= height of each fir tree, y = height of each pine tree.
As per given, we have
x+y = 21 (i)
4x=y+24 (ii)
From (ii),
(iii)
Add (i) and (iii), we get

Put value of x in (i), we get

Hence, the height of each fir tree is 9 meters, and the height of each pine tree is 12 meters.
Answer:
x
Step-by-step explanation: