>>4
２ｓ÷（ｓ−３）÷（ｓ＋５）＝
2s/{ (s-3) (s+5)}
= {a/(s-3)} + {b/(s+5)}
と置いて

分母を払って
2s = a(s+5) + b(s-3)
2s = (a+b)s +5a-3b

a+b = 2
5a-3b = 0

8a = 6
a = 3/4
b = 5/4