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Thepotemich [5.8K]
1 year ago
12

Ava bought some pens for $ 2 each and some pencils for $ 1 each. She bought 3 more pens than pencils and spent a total of $ 12.

How many pencils did Ava buy?
Mathematics
1 answer:
Rudiy271 year ago
5 0

Answer:

Step-by-step explanation:

price of 1 pen= $ 2

price of 1 pencil= $1

total money spent= $12

Let the number of pen be a and number of pencil be b.

 2 a + b = 12   ----------------Equation 1

We have, she bought 3 more pens than pencils

  a - b = 3   ------------------  Equation 2

 Equation 1 +Equation 2,  

   2 a + b +  a - b = 12 + 3

                     3a = 15

                     a = 5

 Substituting in  equation

           5 - b = 3

               b = 2

 Number pencils Ava bought = 2

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Emily is a songwriter who collects royalties on her songs whenever they are played in a commercial or a movie. Emily will earn $
Hitman42 [59]

Answer:

(6,2)

Step-by-step explanation:

Variable Definitions:

​x= the number of commercials

y= the number of movies

Each commercial earns Emily $50, so x commercials would earn her 50x dollars in royalties. Each movie earns Emily $150, so y movies would earn her 150y dollars in royalties. Therefore, the total royalties 50x+150y equals $600:

50x+150y=600

Since Emily's songs were played on 3 times as many commercials as movies, if we multiply 3 by the number of movies, we will get the number of commercials, meaning x equals 3y.

x=3y

Write System of Equations:

​50x+150y=600

x=3y

Solve for y in each equation:

1)  50x+150y=600

   150y=−50x+600

   y=-1/3x+4

2)  x=3y

    y=1/3x

The x variable represents the number of commercials and the yy variable represents the number of movies. Since the lines intersect at the point (6,2) we can say:

Emily's songs were played on 6 commercials and 2 movies.

​

 

4 0
1 year ago
Find the value of $x$ that maximizes $$f(x) = \log (-20x + 12\sqrt{x}).$$ If there is no maximum value, write "NONE".
kakasveta [241]
The function is written as:
f(x) = log(-20x + 12√x)
To find the maximum value, differentiate the equation in terms of x, then equate it to zero. The solution is as follows.

The formula for differentiation would be:
d(log u)/dx = du/u ln(10)
Thus,
d/dx = (-20 + 6/√x)/(-20x + 12√x)(ln 10) = 0
-20 + 6/√x = 0
6/√x = 20
x = (6/20)² = 9/100

Thus,
f(x) =  log(-20(9/100)+ 12√(9/100)) = 0.2553

<em>The maximum value of the function is 0.2553.</em>
5 0
1 year ago
in triangleABC the side lengths are b=13, ac=21 and bc=x. write a compound inequality the represents the range of possible value
tankabanditka [31]

Answer:

8 < x < 34

Step-by-step explanation:

ab = 13, ac = 21, bc = x

The longest side of a triangle must be less than the sum of the other two sides.

If 21 is the longest side:

21 < 13 + x

8 < x

If x is the longest side:

x < 13 + 21

x < 34

Therefore, 8 < x < 34.

3 0
2 years ago
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Read 2 more answers
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saul85 [17]

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Step-by-step explanation:

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(x + 6)(x - 9) = 0

x = -6, 9 (negative value is neglected)

x = 9 units

4 0
2 years ago
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