Calculating Initial Amount given Rate and k

[Simaran Dosanjh 3E]

Given the rate and k and the molar mass of an unknown species, how do I find the initial amount of the species in grams?
We are also given that he added the initial amount in grams to a 500 ml reaction flask.

[Heerali Patel 3A]

The units of k should tell you what the order of the reaction is. You can then find the rate law of the reaction and use the given info. to solve for the (initial) concentration of the species. The question asks for initial amount in grams so you can then use the given info. to convert this concentration to grams.