\(Vtb=\frac{AB+BC}{t1+t2}=\frac{BC+6+BC}{\frac{AB}{24}+\frac{BC}{32}}=\frac{2BC+6}{\frac{BC+6}{24}+\frac{BC}{32}}=27\)
=> BC= 24 => AB= BC + 6 =30
\(VtbAC=\frac{AB+BC}{t1+t2}=\frac{BC+6+BC}{\frac{AB}{24}+\frac{BC}{32}}=\frac{2BC+6}{\frac{BC+6}{24}+\frac{BC}{32}}=27\)
\(\Rightarrow BC=24\Rightarrow AB=BC+6=30\)