设AB距离x(x/5.5)+(12/60)=3.6/[(1/5.5)*(3/4)]
5.5V(速度)=S(距离)(S-3.6)/V + 3.6/(3/4 *V)=5.5+12/60S-3.6+3.6*(4/3)=(5.5+12/60)VS-3.6+3.6*(4/3)=(5.5+12/60)S/5.5S+1.2=S+0.2S/5.5S=1.2*5.5/0.2=33千米
设AB距离x 0.2+(3/4)*5.5*(3.6/x)+5.5*(x-3.6)/x=5.5