chem a level question

does anyone know how to answer this qestion?

When one mole of ammonia is heated to a high temperature, 50% dissociates according to the following equilibrium.
2NH3(g) ⇌ N2(g) + 3H2(g)

What is the total number of moles of gas present in the equilibrium mixture?

the answer is 1.5

thanks

So, think about how many moles of each you had before the eqb was established.

You had 1mol of NH3, and 0 of N2 and 0 of H2

When it reached eqb, 1/2 of the 1mol of NH3 disassociates whilst the other 1/2 remains as 0.5 mol of NH3.

Since there are two moles of NH3, you divide that 0.5 by 2 to find what each mol is, if that makes sense?? So, 0.5/2 = 0.25

One mole of N2 ----> 1 * 0.25 = 0.25 mol
3 mole of H2 -------> 3 * 0.25 = 0.75

0.75 + 0.25 + 0.5 = 1.5 mol all together.

I hope this made sense (I'm sorry if my explanation is a bit dodgy lol)