Are 15g of chorine gas enough to replace 30.0g of bromine from a solution of sodium bromide?

Here, you have chlorine gas reacting with sodium bromide. Also, it is a displacement reaction, meaning that one element (or compound) will replace another one. This gives you:

Cl_2 + NaBr \rightarrow NaCl + Br_2

Then, you only need to balance:
Cl_2 + 2NaBr \rightarrow 2NaCl + Br_2

Using mole ratio, you can find the amount of moles of Chlorine reacting to produce a certain amount of Bromine. Find the weight of both, and find, using proportion, the ratio of mass between the two.