Let's say that A = 1 unit of country A's currency, X = 1 unit of country X's currency, and so on. Using the table given, we can create equations:
A = 2.2X
B = 0.5X
C = 0.1X
D = 4.0X
E = 1.7X

Now, plug these into the answer choices:

A. 4 units of Country A currency --> 4(2.2X) = 8.8X

B. 25 units of Country B currency --> 25(0.5X) = 12.5X

C. 98 units of Country C currency --> 98(0.1X) = 9.8X

D. 3 units of Country D currency --> 3(4.0X) = 12.0X

E. 7 units of Country E currency --> 7(1.7X) = 11.9X

The answer choice with the highest number of units of X (the highest coefficient) is B.

swerve wrote:

For each country listed in the left column of the table, the number in the right column gives the number of units of Country X currency that is equivalent to 1 unit of the country's currency. Which of the following is equivalent to the greatest number of units of Country X currency?

A. 4 units of Country A currency
B. 25 units of Country B currency
C. 98 units of Country C currency
D. 3 units of Country D currency
E. 7 units of Country E currency

The OA is B.

Source: GMAT Prep

Let's examine each answer choice:

A) 4 units of Country A currency = 4 x 2.2 = 8.8 units of Country X currency

B) 25 units of Country B currency = 25 x 0.5 = 12.5 units of Country X currency

C) 98 units of Country C currency = 98 x 0.1 = 9.8 units of Country X currency

D) 3 units of Country D currency = 3 x 4.0 = 12 units of Country X currency

E) 7 units of Country E currency = 7 x 1.7 = 11.9 units of Country X currency

We see that 25 units of Country B currency yield the greatest number of units of Country X currency.

Answer: B