Delta N of 3C(s)+4H2 --> C3H8(g), obviously -6 right

I needed the difference of #'s of mols of this reaction to calculate the variation of the intern energy, and the solution of the problem seemed to say it was -3... Whereas I'm pretty sure it is 1-7=-6... Who is wrong here?
Thanks!

3C(s) + 4H2(g) --> C3H8(g)

The change in moles refers to the moles in the gas phase. The difference in moles is the product moles - the reactant moles.
Dn = 1 - 4 = -3