An order of 12 dozen rollerball pens and 5 dozen ballpoint pens cost $116. A later order 8 dozen rollerball pens and 12 dozen ballpoint pens cost $112. What was the cost of 1 dozen of pens?And how much does 1 dozen pencils cost?

Answers

Answer 1

Answer: r=cost per dozen rollerball pens
b=cost per dozen ballpoint pens
p=cost per dozen pencils
???

ignore pencils

12r+5b=116
8r+12b=112

eliminate
simplify last equation by dividing by 4
2r+3b=28

eliminate r's
multiply 2r+3b=28 by -6 and add to top equation

-12r-18b=-168
12r+5b=116 +
0r-13b=-52

-13b=-52
divide both sides by -13
b=4

plug back in
2r+3b=28
2r+3(4)=28
2r+12=28
minus 12
2r=16
divide by 2
r=8

ballpoint=pencils

1dozen pencils=$4
1dozen rollerbladepens=$8

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D(b) is a function that models the population of deer based on the number of bobcats in an area. What is an appropriate domain for this function?A) D = {all integers}
B) D = (all real numbers}
C) D = {rational numbers}
D) D = {all whole numbers}

Answers

Answer:

Option: D is the correct answer.

D) D = {all whole numbers}

Step-by-step explanation:

As we could see that the number of deer i.e. the population of the deer is based on the number of bobcats in an area.

As the number of bobcats can't be negative or in a fraction or negative it will always be in a whole number (i.e. 0 represents that there are no bobcats, 1,2,.....)

Hence, the correct domain for the function is:

D) D = {all whole numbers}

Option D: all whole numbers, given that the number of bocats cannot be either iirrational or a fraction or a negative number. Only a whole number.

Is the inequality below sometimes, always, or never true?

-2(2x + 9) > -4x + 9

Answers

-2(2x + 9) > -4x + 9
-2(2x) - 2(9) > -4x + 9
-4x - 18 > -4x + 9
+ 4x + 4x
-18 > 9

It is never true.

Answer:

Never True

Step-by-step explanation:

In the neighborhood park there is a circular grassy picnic area, but half of the grass has died. The city wants to replant the grass, but needs to know the square footage of the damaged area. If the circular picnic area is 150 feet across, what is the square footage of the damaged area? Let π = 3.14.A) 471 sq. feet
B) 8831.25 sq. feet
C) 17662.5 sq. feet
D) 35325 sq. feet

Answers

so, πr^2 is the equation for the area of a circle, if we calculate that, it will equal 17662.5

we then half that to get the area (square feet) of the dead grass, which is
8831.25 square feet which means the answer is B.

150 feet across is diameter
find area
but 1/2 is dead
find area then times 1/2

area=pir^2

150=d
d/2=r=150/2=75=r

area=pi75^2
area=5625pi
times 1/2
area=2812.5pi
pi=3.14 for this problem
area=8831.25

B is answer

EXPAND it please and explain
(9r-s/7)(9r+s/7)