Given, $\frac{1}{(3-5 x)(2+3 x)}=\frac{A}{(3-5 x)}+\frac{B}{(2+3 x)}$
By partial fraction
$1=(3 A-5 B) x+(2 A+3 B)$
On comparing the like powers of ' $x$ '
$3 A-5 B=0$...(i)
and $2 A+3 B=1$...(ii)
On solving, we get $A=\frac{5}{19}, B=\frac{3}{19}$
Hence, $A: B=5: 3$