设:大车X辆,小车18-X辆缺芦则30240-[18*x+12*(18-x)]*20=25200解得X=6. 18-6=12答:雀迟需顷扮李要大车6辆,小车12辆
设小货车每次运粗运*件(30240-25200)/20=252大货车磨凳数6辆,小瞎首货车7辆