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densk [106]
3 years ago
11

Solve.

Mathematics
2 answers:
lions [1.4K]3 years ago
6 0

Answer:

b=9,a=12

Step-by-step explanation:

I solved by substitution:

b = 3/4a  ---> plug this into the other equation

a + b = 21   is now    a + 3/4a = 21

Reduce: 7/4a = 21

a = 12

Now solve for b:

b=3/4a is now b=3/4(12)

b=9

Setler [38]3 years ago
6 0

Answer:

a=12 b= 9

Step-by-step explanation:

did the quiz

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6. The dimensions of a living room are 18 ft. by 15 ft. by 8ft. If air weighs 0.08 lb. per cubic foot, the weight of the air in
user100 [1]

The weight of the air in the room is 172.8 lb if the dimensions of a living room are 18 ft. by 15 ft. by 8ft.

<h3>What is a rectangular prism?</h3>

It is defined as the six-faced shape, a type of hexahedron in geometry.

It is a three-dimensional shape. It is also called a cuboid.

It is given that:

The dimensions of a living room are 18 ft. by 15 ft. by 8ft.

The volume of the living room = volume of the cuboid:

V = length×width×height

V = 18×15×8

V = 2160 cubic ft

The weight of the air = 0.08 lb. per cubic foot

The weight of the air in the room = 0.08×2160

The weight of the air in the room = 172.8 lb

Thus, the weight of the air in the room is 172.8 lb if the dimensions of a living room are 18 ft. by 15 ft. by 8ft.

Learn more about the rectangular prism here:

brainly.com/question/21308574

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7 0
1 year ago
What value of c makes the trinomial below a perfect square x2 + 7x + c?
Daniel [21]
We have that
x²<span> + 7x + c
</span><span>Group terms that contain the same variable
</span>(x² + 7x )+ c
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Rewrite as perfect squares

(x+3.5)²+ c-3.5²
so
c-3.5² must be zero
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the answer is
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5 0
3 years ago
Read 2 more answers
How do we solve this?<br> (No need to find x)
Genrish500 [490]

Answer:

Hi,

Step-by-step explanation:

We can't solve that but reduce it to the same denominator.

\dfrac{x+5}{x}+\dfrac{x+8}{x-1}\\\\=\dfrac{(x+5)(x-1)+x(x+8)}{x(x-1)}\\\\=\dfrac{x^2+5x-x-5+x^2+8x}{x(x-1)}\\\\=\dfrac{2x^2+12x-5}{x(x-1)}\\

5 0
2 years ago
A sample of 12 measurements has a mean of 8.5 and a sample of 20 measurements has a mean of 7.5. Find the mean of all 32 measure
nalin [4]
Multiply 8.5 by 12, multiply 7.5 by 20, add them together to get 252, then divide that by 32 to get 7.875. 7.875 is the mean of all 32 measurements
6 0
3 years ago
Write an equation for each line in slope-intercept form.​
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Answer:

Line 1 : y = -2x - 5

Line 2 : y = -3x + 3

Step-by-step explanation:

note the slope, and then note the y intercept

8 0
2 years ago
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