$\begin{cases}-3x+4y=-20\\y=x-4\end{cases}\\\\\\-3x+4(x-4)=-20\\\\-3x+4x-16=-20\\\\x-16=-20\quad|+16\\\\x-16+16=-20+16\\\\\boxed{x=-4}\\\\\\y=x-4\\\\y=-4-4\\\\\boxed{y=-8}$

Answer C.

4 0

3 years ago

X is normally distributed with mean 250 and standard deviation 40. what value of x does only the top 15% exceed?

lubasha [3.4K]

The top 15% (85th percentile) is the cutoff value $x$ such that

$\mathbb P(X\le x)=\mathbb P\left(\dfrac{X-250}{40}\le\dfrac{x-250}{40}\right)=\mathbb P(Z\le z)=0.85$

where $z$ is the corresponding cutoff for the standardized normal distribution. We have $z\approx1.0364$ , and so

$\dfrac{x-250}{40}=z\implies x\approx291.456$

3 0

3 years ago

Please help mee Idk.

Ira Lisetskai [31]

Answer:

x(1.05)+4.00

Step-by-step explanation:

He bought x pens for 1.05 each and you have to add the $4 shipping fee to it

Hope this Helps

8 0

3 years ago

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What is 16x9+67x9 can someone help me?

vazorg [7]

Answer: 747

Step-by-step explanation:

16x9+67x9

First multiply 16 and 9 which is equal to 144

144+67x9

now multiply 67 and 9 which is equal to 603

144+603

Now add 144 and 603 which is equal to 747

So the answer to 16x9+67x9 is 747

5 0

3 years ago

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