In order to make b the subject of this equation, we must isolate it on the left side. We can do this by following these steps:
[tex]P = 2a+b[/tex]
Subtract b from both sides
[tex]P - b = 2a+b-b[/tex]
[tex]P-b=2a[/tex]
Subtract P from both sides
[tex]P-b-P=2a-P[/tex]
[tex]-b=2a-P[/tex]
Now, we have isolated b, but it is negative. We can fix this by multiplying both sides of the equation by -1.
[tex]-(-b)=-(2a-P)[/tex]
[tex]b=-2a+P[/tex]
Which is your final answer.
[tex]b = -2a+P[/tex].
Hope that helped! =)
