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3 years ago

-5y y=-2 -3x 6y=-12 substitution

Mathematics

1 answer:

IrinaK [193]3 years ago

5 0

The answer would be x=4 and y=-2.

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What percent of 72 is 9? 1/8% 1 1/4% 12 1/2% 125%

USPshnik [31]

Answer:

$12\dfrac 12\%$

Step by step explanation:

$\text{Let it be}~ x\%,\\\\~~~~~72 \cdot x \% = 9\\\\\\\implies 72\cdot \dfrac{x}{100} = 9\\\\\\\implies x = \dfrac{9 \times 100}{72}\\\\\\\implies x = \dfrac{100}{8}\\\\\\\implies x = \dfrac{25}2\\\\\\\implies x = 12 \dfrac 12\\\\\\\text{Hence 9 is}~ 12\dfrac 12\% ~ \text{of}~ 72$

4 0

2 years ago

Mathew mowed lawns for 3 hours and earned $6.20 per hour. Then he washed windows for 4 hours and earned $6.90 per hour. What wer

Shtirlitz [24]

Answer:

$6.60

Step-by-step explanation:

6.20 x 3 = 18.60

6.90 x 4 = 27.60

18.60 + 27.60 = 46.20

46.20 ÷ 7 = 6.60

6 0

3 years ago

Elena cashed a check for $$4350 at Quick Cash. The fee to cash

serious [3.7K]

Answer:

522

Step-by-step explanation:

5 0

3 years ago

A scientist running an experiment starts with 100 bacteria cells. These bacteria double their population every 15 hours. Find ho

emmasim [6.3K]

Answer

It will take (t) = 24 hours to reach 300 .

Step by step explanation

It doubles every 15 hours. initial bacteria = 100

We need to find how long it take for the bacteria cells to increase to 300.

300 = 100(2)^t/15

300/100 = 2^t/15

3 = 2^t/5

Taking "ln" both sides, we get

ln(3) = t/15 ln(2)

t/15 = ln(3)/ln(2)

t/15 = 1.585

t = 1.585 * 15

t = 23.78 hours

t = 24 hours to nearest whole hours.

Thank you.

6 0

3 years ago

I need to make a matrix in reduced row echelon form

a_sh-v [17]

Let the three apartments be A, B & C

The rent of A is $x

The rent of B is $y

The rent of C is $z

So x + y + z = 1600 .......(1)

Now

Maintenance of A is 20% of x = 0.20x

Maintenance of B is 20% of y = 0.20y

Maintenance of C is 25% of z = 0.25z

0.20x + 0.20y + 0.25z = 345

Multiplying by 100 we get

20x + 20y + 25 z = 34500

Dividing by 5 we get

4x + 4y + 5z = 6900 .......(2)

Monthly fee of A is 10% of x = 0.10x

Monthly fee of B is 20% of y = 0.20 y

Monthly Fee of C is 10% of z = 0.10z

Now

0.10x + 0.20y + 0.10 z= 1820 - 1600

0.10x + 0.20y + 0.10z = 220

Multiplying by 100 we get

10x + 20y + 10z = 22000

Dividing by 10

x + 2y + z = 2200 ....(3)

Making a Matrix of equation (1), (2) & (3)

$\left[\begin{array}{ccc}1&1&1\\4&4&5\\1&2&1\end{array}\right] \left[\begin{array}{c}x\\y\\z\end{array}\right] =\left[\begin{array}{c}1600\\6900\\2200\end{array}\right]$

is the required matrix

7 0

4 years ago

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