Solve the following initial value problems:

$a\frac{dy}{dx}=\frac{x-2y+1}{2x+3y+5},$ with $y(0)=5$;

$b\frac{dy}{dx}=\frac{2x+5y-1}{x-y-2},$ with $y(1)=0$;

$c\frac{dy}{dx}=\frac{x-y-1}{3x-3y+5},$ with $y(-1)=1$;