How can I use Poisson bracket to find P in a canonical transformation?

[Apashanka das]

Homework Statement

q,p transforms canonicaly to Q,P where given Q=q(t+s)+(t+s)p ,t is time and s is constt
To find P

Homework Equations

Poisson bracket {Q,P}_qp=1

The Attempt at a Solution

Using Poisson bracket I find (t+s)*(dP/dp-dP/dq)=1

 

[Chandra Prayaga]

Start with the definition of a Poisson bracket.