設(shè)慢車開(kāi)出x小時(shí)后,兩車相遇；則相遇時(shí),慢車共行駛了50x千米,快車行駛的時(shí)間是(x-1.5)小時(shí),快車共行駛了60(x-1.5)千米；根據(jù)題意,有方程：
50x+60(x-1.5)=270
50x+60x-90=270
50x+60x=270+90
110x=360
x=36/11
算式方法：
1.5+(270-1.5×50)÷(50+60)
=1.5+(270-75)÷110
=1.5+195÷110
=1.5+39/22
=3/2+39/22
=33/22+39/22
=36/11 小時(shí)
答：慢車開(kāi)出36/11小時(shí)后,兩車相遇.