Solve the system of equations by any convenient method, if a solution exists.
\begin{cases} 3x - 7y = 30 \\ 6x - 9y = 45 \end{cases}
Select the correct answer below and, if necessary, fill in any answer boxes to complete your choice.
A. The solution is x = and y = . (Type integers or simplified fractions.)
B. There are infinitely many solutions.
C. There is no solution.