Answer:
$60 for a noble fir, and $40 for a douglas fir
Step-by-step explanation:
Let x represent the number of noble fir trees
Let y represent the number of douglas fir trees
We can set up a system of equations to solve this problem
5x + 3y = 420
12x + 9y = 1080
We can use elimination method to solve this. 9 is a multiple of 3, so we'll multiply the first equation by -3 to get...
-15x - 9y = -1260
12x + 9y = 1080
Now add them together...
-3x = -180 now solve for x...
x = 60
If x = 60, them
5(60) + 3y = 420 now solve for y
300 + 3y = 420
3y = 120
y = 40
Answer:
120960
Step-by-step explanation:
Given that a librarian has a set of ten different books, including four different books about Abraham Lincoln.
The librarian wants to put the ten books on a shelf with the four Lincoln books next to each other, somewhere on the shelf among the other six different books.
First arrnage the 6 other books in the shelf.
This can be done in 
Now arrange the 4 books of Lincoln
This can be done in 
Now we have 7 places to insert Lincoln books including two corners and in between.
Thus this can be done in 7 ways
Total no of ways = 
Answer:
25 sheets of plywood will be needed
Step-by-step explanation:
Each sheet of plywood measures
.
We have to cover the surface of the house, minus the surface of the hole of the stairs.

To know how many sheets will be needed, we divide the surface to be covered by the surface of each sheet

As we can't buy 0,75 of a sheet, we round it up, i.e. we will need 25 sheets of plywood for subflooring.
Answer:
I have no clue
Step-by-step explanation:
i dont lnow