The way the expression is typed is probably different from the book for lack of parentheses. When it is type-set, parentheses are not required on the numerator and denominator. When interpreted on one single line, they are required, or else a completely different expression results.
Also, I think 9p^b at the beginning should read 9p^2 (just a guess).
Please check what I assume is the correct interpretation.
(9p^2)/(p^2-b^2) - (p-b)/(p+b)
=(9p^2)/((p+b)(p-b)) - (p-b)²/((p+b)(p-b))
=(9p^2-(p-b)²)/((p+b)(p-b))
=(3p+p-b)(3p-(p-b))/((p+b)(p-b))
=(4p-b)(2p+b)/((p+b)(p-b))
Subtract. Simplify by removing a factor of 1 when possible.
(9p^b)/p^2-b^2 - p-b/p+b.
Thank you. These problems, I don't understand at all. I'm sorry.
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