A fibres 5 shots to B's 3 but A kills only once in 3 shots while B kills once in 2 shots. When B has missed 27 times, A has killed

Let the total number of shots be x. then, 

Shots fired by $A=\frac{5}{8}x$; Shots fired by $B=\frac{5}{8}x$

Killing shots by $\mathrm{A}=\frac{1}{3}$ of $\frac{5}{8}\mathrm{x}=\frac{5\mathrm{x}}{24}$

Shots missed by $B=\frac{1}{2}$ of $\frac{3}{8}x=\frac{3x}{16}$

$\therefore \frac{3x}{16}=27$ or $x=\left(\frac{27\times 16}{3}\right)=144$

Birds killed by $A=\frac{5x}{24}=\left(\frac{5}{24}\times 144\right)=30$