P/E and justified P/E (Trailing)

CFA Level II Equities
#1

From CFAI book:

[question removed by moderator]

Why are these two number different wouldn’t the direct calculation of P0 / E0 be the same as (1+g)*(1-d)/(r-g)

#2

Ignore the question : I figured out trailing and leading P/E help in valuing the actual P/E

#3

They’re different because the market price of the stock is lower than what the Gordon growth model says that it should be.

There’s no reason for them to be the same, which is the point of the justified multiple.