How many ships of the line could overwhelm a modern frigate?

How many ships of the line would it take to overwhelm a modern frigate?

There is no single number: it depends on the frigate, its ammunition and whether it is allowed to withdraw. A modern frigate should be fast enough to escape.

The number depends on the frigate and how much ammunition it carries. Its ability to disengage is another decisive condition in the hypothetical. Modern frigates are credited with speeds above twenty knots, which would let them escape sailing ships. A scenario that requires the frigate to remain and fight would therefore produce a different answer from one that allows withdrawal.