Step 1: Assign variables.
Let the number of female students be \( f \). Then male students = \( 2f \).
Let the number of US citizen students be \( x \), then international students = \( 3x \).
Step 2: Total students equation.
\[
f + 2f = 3f = \text{total students} = 36 \Rightarrow f = 12, \quad 2f = 24.
\]
So, female students = 12.
Step 3: Now apply the international/US citizen relationship.
\[
x + 3x = 4x = 36 \Rightarrow x = 9.
\]
So, US citizen students = 9.
Step 4: Comparison.
Quantity A = 9, Quantity B = 12
\[
\Rightarrow \text{Quantity B is greater.}
\]
Wait! There seems to be a contradiction. Since both variables depend on the same total of 36, and give different values (female = 12, US = 9), we must **reconcile the constraint**.
Let's try solving the equation combining both relationships:
- Let \( f \) be number of female students,
- Then male = \( 2f \)
- Total students = \( f + 2f = 3f \)
- Also, let US students = \( x \), international = \( 3x \)
- Total students = \( x + 3x = 4x \)
So, both \( 3f = 36 \) and \( 4x = 36 \) hold.
\[
f = 12, \quad x = 9
\Rightarrow \text{Quantity A (US) = 9, Quantity B (female) = 12.}
\]
Step 5: Final conclusion.
So,
\[
\boxed{\text{Quantity B is greater.}}
\]