If there is no friction, the force that moves the box forward horizontally must be matched by the same force.
If there is friction, then the force moving it forward = frictional force + the additional force you need to add.
Just because the book is moving doesn't tell you anything about the forces on it, or even whether there ARE any.
Just look at Newton's first law of motion, and this time, let's try and THINK about it too. It says something to the effect that any object continues in constant, uniform MOTION ..... UNLESS acted on by an external force.
There are several approaches. The most favourable one (in my opinion) is this one:
1. Asking a question
2. Doing a research (how to answer this question)
3. Creating a hypothesis (NOT a thesis!)
4. Experimenting (to prove the hypothesis)
5. Analysing results from the experiment
6. Writing a thesis
Answer: 
Explanation:
Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.
The combined gas equation is,
where,
= initial pressure of gas at STP = 1 atm
= final pressure of gas = 2.67 atm
= initial volume of gas = 
= final volume of gas = ?
= initial temperature of gas at STP = 
= final temperature of gas = 
Now put all the given values in the above equation, we get:
Thus the final volume will be
