If an item that originally cost $14 is decreased to $12, what is the percentage of decrease in the item?
2 answers:
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<h3>Answer: Choice B</h3>
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Explanation:
If you graphed the equation 2x-5y = 14, you'll find it has a positive slope. It turns out the slope in this equation is 2/5, which is positive. A positive slope means the line goes uphill as you move from left to right. This means we can rule out choice because of this (since we want the line to slope downward).
Now let's turn to choice D. If we multiply both sides of the first inequality by -1, then we go from to
. Note the inequality sign flips. This always happens when we multiply both sides by any negative number. The inequality
implies that the shaded region will be above the boundary line, but this contradicts the drawing which shows the shaded region is below the diagonal boundary line. We can rule out choice D because of this. Choice A can be ruled out for similar reasoning.
You should find that only choice B is left. The diagonal line is 2x+5y = 14, and we shade below this boundary line, as well as shading to the right of the y axis (to indicate all values have positive x coordinates). Values on the boundary count as solution points as well.
