the cost of the installation is 30 + 20x, where x represents the number of outlets installed in the home. so, this question can be rephrased as
what is 30 + 20x?
furthermore, that's just a linear expression; if you have the value of x, you can just plug it in to find 30 + 20x, and if you have the value of 30 + 20x, you can just solve to find x. therefore, this question can be further rephrased as
what is x? or, how many outlets were installed?
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statement (1)
x = 3
sufficient.
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statement (2)
remember that SUM = AVERAGE x NUMBER.
therefore, if the average cost per outlet was $30, then this equation gives
total cost = (30)(x).
but we also know that the total cost is 30 + 20x, per the prompt. therefore, we can set up the following equation:
30x = 30 + 20x
that's a linear equation, so it can be solved for x.
sufficient.
alternatively, you can use the original definition of average, which is really just a rearranged version of the formula above:
AVERAGE = SUM / NUMBER
therefore,
30 = (30 + 20x) / x
multiply by x on both sides to give 30x = 30 + 20x, the same linear equation that was found above.
Ron has been teaching various standardized tests for 20 years.
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Pueden hacerle preguntas a Ron en castellano
Potete chiedere domande a Ron in italiano
On peut poser des questions à Ron en français
Voit esittää kysymyksiä Ron:lle myös suomeksi
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Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.
Yves Saint-Laurent
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