If f(x)=(2x+5)/(x^2+x+5) , then f(f(-1)) is equal to

$f(x)=\frac{2x+5}{x^2+x+5}$

so $f(-1)=\frac{2(-1)+5}{(-1)^2+(-1)+5}=\frac{3}{5}$

so $f(f(-1))=\frac{2×\frac{3}{5}}{\frac{3^2}{5^2}+\frac{3}{5}+5}=\frac{155}{149}$