Im a currently struggling with these two enthalapy problems.

#1 If F2(g) + H2(g) --> 2HF(g) H= -542kJ, what is the Standard Heat of Formation for HF?

Is this going to be the same as the enthalaphy of the reaction = -542 or is going to be half of that = -271kJ.

#2 When 1.00g of ammonia decomposes to give hydrogen and nitrogen, 2.71kJ of heat are absorbed. What is the heat of formation of ammonia?

I wrote out the reation and saw that it could be 92kJ or -46.0kJ

If anyone could help me with these two problems it would be greatly appreciated.