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Serggg [28]
3 years ago
13

21 is 75% of what amount

Mathematics
2 answers:
podryga [215]3 years ago
6 0
21 is 75% of 28. You already know that to make 100, you need 4 25's. 75 is three 25's. You take 21 and divide it by three to get seven. Then you take your past knowledge and multiply 7 by 4 and get 28.
zysi [14]3 years ago
3 0
In the given question it is required to find an unknown amount from all the details given in the question. It is given that 21 is the 75% of the unknown number.
Let us consider the amount = x
Then we can write the equation as
75x/100 = 21
75x = 21 * 100
75x = 2100
x = 2100/75
  = 28
So the correct amount is 28. <span>. I hope to have made the procedure clear for finding the solutions of such problems.</span>



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Match the pairs of equations that represent concentric circles. Tiles
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(x - xc)^2 + (y - yc)^2 = r^2.

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3) You can transform the equations given in your picture to the form (x -xc)^2 + (y -yc)^2 = r2 by completing squares.

Example:

Equation: 3x^2 + 3y^2 + 12x - 6y - 21 = 0

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extract common factor 3: 3 (x^2 + 4x) + 3(y^2 -2y) = 3*7

=> (x^2 + 4x) + (y^2 - 2y) = 7

complete squares: (x + 2)^2 - 4 + (y - 1)^2 - 1 = 7

=> (x + 2)^2 + (y - 1)^2 = 12 => center = (-2,1), r = √12.

equation: 4x^2 + 4y^2 + 16x - 8y - 308 = 0

rearrange: 4x^2 + 16x + 4y^2 - 8y = 308

common factor 4: 4 (x^2 + 4x) + 4(y^2 -8y) = 4*77

=> (x^2 + 4x) + (y^2 - 2y) = 77

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5 0
3 years ago
Find the measurement
xenn [34]

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6z + 7  = 8z - 9

8z - 9 = 6z + 7

Add sides 9

8z - 9 + 9 = 6z + 7 + 9

8z = 6z + 16

Subtract sides 6z

- 6z + 8z =  - 6z + 6z + 16

2z = 16

Divide sides by 2

\frac{2z}{2}  =  \frac{16}{2}  \\

z = 8

Thus ;

NP = 8z - 9

NP = 8(8) - 9

NP = 64 - 9

NP = 64 - 4 - 5

NP = 60 - 5

NP = 55

Done...

♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️

6 0
3 years ago
Guy what 5x4 please help me
Archy [21]

Answer:

20

Step-by-step explanation:

5 0
3 years ago
Read 2 more answers
3(6+4y)<br> hurry uppp pleaseeeee
Ahat [919]

Answer:

=12y+18

Step-by-step explanation:

=(3)(6+4y)

=(3)(6)+(3)(4y)

=18+12y

=12y+18

4 0
3 years ago
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