The idea of public reason isn't about the right answers to all these questions, but about the kinds of reasons that they ought to be answered by.

[E]ach person is to have an equal right to the most extensive basic liberty compatible with a similar liberty for others.

There are various ways you might define the common good, but that would be one way you could do it.

An injustice is tolerable only when it is necessary to avoid an even greater injustice.

A political conception just applies to the basic structure of a society, its institutions, constitutional essentials, matters of basic justice and property, and so on.

In all sectors of society there should be roughly equal prospects of culture and achievement for everyone similarly motivated and endowed. The expectations of those with the same abilities and aspirations should not be affected by their social class.

You might say that, if citizens are acting for the right reasons in a constitutional regime, then regardless of their comprehensive doctrines they want every other citizen to have justice. So you might say they're all working together to do one thing, namely to make sure every citizen has justice. Now that's not the only interest they all have, but it's the single thing they're all trying to do. In my language, they've striving toward one single end, the end of justice for all citizens.