According to question $\Rightarrow$A = 2B,   B = 2C

‘C’ takes 54 minutes the ‘B’ takes half of  the time =

$B\Rightarrow \frac{54}{2}=27\text{\hspace{0.17em}\hspace{0.17em}mins}$

$A=\frac{27}{2}=13.5\text{\hspace{0.17em}\hspace{0.17em}mins}$