Given:

[SO4^2-] in a 0.2M NA2SO4 solution

How do I express this in meq/l?

There are .2*2 equivalents per liter, so there must be 1000 times that of meq/l. If you want it in grams, that is another conversion.

So, the answer would be 400 meq/l. Do you need to do something with formula weights?
Still confused

You wanted the answer in meq/L. The answer is 400 meq/L. What are you confused about? You don't need to do anything with formula weights unless you want to convert to grams/L. And you could have done that without going through the meq/L step.

Thanks a bunch!

You're welcome! I'm glad I could help clarify things for you. If you have any more questions, feel free to ask!