1.

Suppose there are x kilograms of oil.

The remaining oil is X-6kg, 60% lighter than the original total mass, 60% X- 1kg.

The formula is x-6 = 60% x-1.

x = 12.5

Answer: crude oil 12.5 kg.

2.

Set a cargo ship to sail at the speed of x kilometers per hour.

The speed of the cargo plane is divided by the distance of the cargo plane and the travel time of the cargo plane.

Among them, the total distance traveled by the cargo ship minus the distance traveled by the passenger ship is 4.5× 28km, and then minus 100km.

334-4.5× 28-100 =108km

Distance divided by time is 108 ÷ 4.5 = 24 km/h.

The total distance of the train,100km plus the distance of two passenger ships.

4.5 × ( 28 + x ) + 100 = 334

x = 24

A: The speed of the freighter is 24 kilometers per hour.