Let
be the cost, respectively, of a notebook and a pen. If you buy 2 notebooks and 3 pens (which we know is a cost of $14.50), you spend 
Similarly, if you buy 1 notebook and 2 pens (which we know is a cost of $7.50), you spend 
These two equations form the following system:

Multiply the second equation by 2:

Subtract the first equation from the second:

So, a pen costs 0.5 dollars. Plug this equation in the second equation:

Answer:
d = -8
Step-by-step explanation:
Isolate the variable, d. Note the equal sign, what you do to one side, you do to the other. Divide -4 from both sides of the equation:

d = -8 is your answer.
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Answer:That is not the solution explanation: because if you put the 0 in place of the x in the equation, y would have to equal 6. If you put the -2 in place of the y then x would have to equal 8.
Simpler explanation: 0 + -2 = -2 not 6
<em>so</em><em> </em><em>the</em><em> </em><em>answer</em><em> </em><em>is</em><em> </em><em>of</em><em> </em><em>option</em><em> </em><em>B</em><em>.</em>
<em>Hope</em><em> </em><em>this</em><em> </em><em>will</em><em> </em><em>help</em><em> </em><em>u</em><em>.</em><em>.</em><em>.</em><em>.</em>
Answer: 0.3821
Step-by-step explanation:
Let x be the random variable that represents the wages.
Given: Workers have an average wage of $9.00 per hour with a standard deviation of $0.50.
The probability of obtaining a sample mean less than or equal to $8.85 per hour:

The required probability = 0.3821