If a quarter of the first shipment is 15 tons, then the first shipment is A=x*0.25+ 15.

The second shipment is B=(x-A)*0.4+20,

The third shipment is C=(x-A-B)*0.75+20.

Finally, D = 15 = X-A-B-C remains.

X asked for it himself.

2 A bottle has a certain volume of alcohol, and B bottle has a certain volume of alcohol.

Pour a third from bottle A to bottle B, bottle A A2/3 and bottle B A1/3+B.

Pour out three fifths of bottle A from bottle B, with bottle A being A2/3+(A 1/3+B)3/5 and bottle B being (A 1/3+B)2/5.

The alcohol in bottle B is two fifths of that in bottle A, [A2/3+(A1/3+B) 3/5] 0.4 = (A1/3+B) 2/5.

Calculate A/B=