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Answer: 8 = 4p (choice A)</h3>
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Explanation:
p is a placeholder for a number. Think of it like a box where a number goes inside.
In this case, p is the price of one pack of pencils.
We can use a proportion to help set up an equation
(4 packs)/(8 dollars) = (1 pack)/(p dollars)
4p = 8*1 ... cross multiply
4p = 8
8 = 4p which points to choice A as the answer.
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Alternative method:
4 packs = 8 dollars
1 pack = p dollars
Multiply both sides of the second equation by 4 and you'll get
4 packs = 4p dollars
Then replace the "4 packs" on the left hand side with "8 dollars"
8 dollars = 4p dollars
that turns into
8 = 4p
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Yet another method:
We know it's $8 for 4 packs. This must mean it is 8/4 = 2 dollars per pack.
If p is the cost of one pack, then p = 2.
Now plug p = 2 into each of the four answer choices. You should find that only 8 = 4p results in a true equation.
Choice B is false because 8 = 4/p turns into 8 = 4/2 and that becomes 8 = 2, which is a false equation. Choices C and D are similar stories.
