Before leaving on a trip, Ms. Rodes exchanged 500 United States dollars

[BTGModeratorVI]

Before leaving on a trip, Ms. Rodes exchanged 500 United States dollars for German marks at an exchange rate of 1.55 marks per dollar. When the trip was canceled, she exchanged the total amount of marks for dollars at an exchange rate of 0.60 dollar per mark. What was the total amount, in dollars, that she lost through the two transactions?

(A) $20.00
(B) $30.00
(C) $35.00
(D) $45.00
(E) $55.00

Answer: C
Source: Official guide

[Brent@GMATPrepNow]

Before leaving on a trip, Ms. Rodes exchanged 500 United States dollars for German marks at an exchange rate of 1.55 marks per dollar. When the trip was canceled, she exchanged the total amount of marks for dollars at an exchange rate of 0.60 dollar per mark. What was the total amount, in dollars, that she lost through the two transactions?

(A) $20.00
(B) $30.00
(C) $35.00
(D) $45.00
(E) $55.00

Answer: C
Source: Official guide

Let's use equivalent ratios to solve this question

Ms. Rodes exchanged 500 United States dollars for German marks at an exchange rate of 1.55 marks per dollar.
In other words: marks/dollars = 1.55/1

So, we can write: x/500 = 1.55/1
Cross multiply to get: x = (500)(1.55) = 775
So, $500 is equal to 775 marks

When the trip was canceled, she exchanged the total amount of marks for dollars at an exchange rate of 0.60 dollar per mark.
So she now wants to exchange her 775 marks to dollars.
The new exchange rate is: dollars/marks = 0.6/1
So, we can write: y/775= 0.6/1
Cross multiply to get: y = (775)(0.6) = 465 dollars

What was the total amount, in dollars, that she lost through the two transactions?
Ms Rodes started with $500 and now has 465 dollars
$500 - $465 = $35

Answer: C

Cheers,
Brent