Answer:
His recoil velocity is 0.269 m/s to the East
Step-by-step explanation:
This question is easily solved by using the law of conservation of linear momentum.
The formula for the momentum is

, where m is the mass and v its speed.
The person + the book are at rest which means their momentum is

After the book is released, they both start to move and their combined momentum is

Where
are the mass and speed of the person respectively and
are the mass and speed of the book
Knowing that
(positive speed is assumed to the right or East), and the total momentum is zero:
=>


Since the sign of
is positive, it's directed to the East