IBC Rate Regulation - solving for price lag

[Koloman]

This is unlikely to be tested, but it's the first use of math I've come accross so far in my readings . . .

I was looking at how they solve the price lag model for price when the expected underwriting result does not equal 0. The substitutions the author makes on Page 10 between the first and second line do not make sense based on the definition of "Lt" on Page 9.

Definition of Lt . . .
Page 9: Lt = E(Lt-1)+et+vt
Page 10: Lt = E(Lt)+et+vt

Anyone else notice this?