Each big oil drum contains 6 kilograms of oil, and each small oil drum contains 2 kilograms of oil. There are 50 big oil drums and small oil drums. How many oil drums are there with 60kg more oil than small oil drums? 50 are all big oil drums.

Then the big oil drum is more than the small oil drum: 50 * 6 = 300 (kg)

Replace, change the small oil drum into a large oil drum.

Every time you change a big oil drum, it is much less than a small one: 6+2 = 8 (kg).

Much less: 300-60 = 240 (kg)

Change (small oil drum available): 240/8 = 30 (times) (pieces)

Oil drums: 50-30 = 20 (pieces)

I don't know if I can be satisfied.

Hehe, come on! If you don't understand, ask again and answer honestly!