5.2-2.7=2.5

2.5*2=5

5.2-5=0.2

This oil weighs 5 kilograms.

The barrel weighs 0.2 kg.

Analysis:

A barrel of oil ***5.2 kilograms, after half of it is used up,

Oil drums ***2.7 kg, therefore,

The weight of oil used is 5.2-2.7=2.5 (kg),

So the total weight of oil =(5.2-2.7)x2=5 (kg).

Bucket weight = 5.2-5 = 0.2kg.