A substance (CD) decomposes into C and D.

CD(g)  C(g) + D(g)
At the temperature of the experiment, 15.0 percent of CD is decomposed when equilibrium is established.
a) If the initial concentration of CD is 0.200 mol/L, what are the equilibrium concentrations of CD, C and D?

I wanted to know the steps of how to calculate this...

if 15 percent is cecomposed, then .85*.200M is the concentration of CD, and .15*.200 is the concentration of C, and D.

Check my thinking.

yes it is thank you very much

The equation is
2NH3 <=> N2 + 3H2
1 mole of NH3 injected intoa 1L flask
0.3 moles of H2 was found
the concentration of N2 at equlibrium is 0.1M

how do I find the concentration of NH3 at equlibrium?

answered above.