设每车装x吨
(5x+5)÷3/8=14x
40x+40=42x
2x=40
x=20
共运20*14=280吨
如果是算式：
5÷（14×3/8-5）×14
=5÷（5.25-5）×14
=5÷0.25×14
=20×14
=280吨