hess' law ethnalpy cycle (alternative route)?

Question

ok i'm used to seeing the enthalpy cycle with 3 arrows for the alternative route ,why would it have four ,as in this following equation:

N2O4(g) -----------------> 2NO2 (g)

ok for those who can't see what i mean from the one equation..in the book it looks like:

N2O4(g)------------------>2NO2(g)
- (up arrow to here)
-
-
-
- -
v (down arrow) -
N2(g)+2O2(g)-------------------------->2NO(g)+O2(g)

there's something mising...on the bottom right


this equation:

2NO(g) +O2(g)

with an arrow pointing upwards to the 2NO2(g)

Answer 1

I only see one arrow. You haven't given us a complete account of the problem.

Additional Details:

You apparently have three arrows because you're to consider four steps instead of three in getting from N2O4 to 2NO2. steps