Price per gallon \(p\) equals to \(d+0.04d\) (dealer's price \(d\) plus 4%) plus \(0.18\), so \(p=d+0.04d+0.18\) --> \(p=1.04d+0.18\) --> \(d=\frac{p-0.18}{1.04}\).

Answer: D.
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I picked C. I divided the 1.04 with P before subtracting 0.18. What rule is there that I am unaware of here?

Substraction has to be done first, & then the whole term to be divided by 1.04

ok lemme offer my 6 pence. Answer is D.

Why border ourselves solving formulars when our aim isn't to become Enstein but to pick the right answer.
we can always solve confusing questions by picking a simple number. the simplest number here is one so we don't do any Enstein level calculation.
let dealers price (d) be 1. so adding 4% to dealers price is d+ 4% of d. i.e. 1 + 4% of 1 which is 1 + 0.04. then add 0.18 to the value.
Now 1.04 + 0.18. this is now 1.22. you have the gasoline stations price (p) as 1.22 dollars.
Now sub 1.22 in the options to know which option gave you d = 1. d must equal 1 because you earlier picked 1 as the value of d in the question.

PS: always remember to start from E upwards.
thank you.

question stem can be written as p = d + 4% of d +0.18
=> p = d(1+0.04)+0.18
=> p-0.18 = d(1+0.04)
d = p-018 /(1.04)

The problem states "...then adding a gasoline tax of $0.18 per gallon"

So, why is this not P = 1.04d + 0.18d instead of P = 1.04d + 0.18

Please help!

Thanks

Coolfool

Because p in the solutions above is already the price per gallon (the price of ONE gallon). Please re-read the solutions above.

Hope it helps.
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Hi All,

This question can be solved by TESTing VALUES.

P = Price per gallon CHARGED
D = Price per gallon for the Dealer

We're told that the Dealer price has a 4% tax AND 18 cents per gallon added on.

So, I'm going to pick a nice round number for D.

D = $10
P = $10 +4%($10) + 18 cents = 10.40 + .18 = 10.58

Now, we plug in D = 10 and P = 10.58 into the answer choices; there's only one answer that matches...

Final Answer:

GMAT assassins aren't born, they're made,
Rich
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In a certain state, gasoline stations compute the price per gallon "p", in dollars, charged at the pump by adding a 4 percent sales tax to the dealer's price per gallon "d", in dollars . . .
We can write: p = d + 4% of d
= d + 0.04d
= 1.04d
So, we have: p = 1.04d

. . . and then adding a gasoline tax of $0.18 per gallon.
We get: p = 1.04d + 0.18

Which of the following gives the dealer's price per gallon "d" in terms of the price per gallon "p" charged at the pump?
We need to take p = 1.04d + 0.18 and solve for d

Take: p = 1.04d + 0.18
Subtract 0.18 from both sides to get: p - 0.18 = 1.04d
Divide both sides by 1.04 to get: (p - 0.18)/1.04 = d

Answer: D
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Hi
Using this approach, wouldn't there be 2 possible answers (B & D)? Since substituting p = 1.22 into option B gives us d = 1.22/1.22 = 1?

Hi achanak,

Yes, while using TEST IT is a great option for this question, using D = 1 does lead to two answers that 'match' what we're looking for (the correct answer and one of the incorrect ones). This is ultimately why you typically should not 'TEST' the numbers 0 or 1 when dealing with PS questions. Using a slightly larger number (I used D = 10 in my explanation above) will likely lead you to just one matching answer (re: the correct one).

GMAT assassins aren't born, they're made,
Rich
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