Two-fifths of the freight in a warehouse was originally shipped out, and then 8400 tons were brought in, 30% higher than the original. How many tons of original goods are there in the warehouse?

Originally regarded as 1 unit.

After 2/5 shipment, there is still 1-2/5=3/5.

So it is 8400/(1+30%-3/5) = 8400/0.7 =12000 tons.

There are two warehouses. Warehouse A has 2000 bags of grain. After taking out a quarter and putting it in warehouse B, the grain in the two warehouses is equal. How many are A and B?

Solution: A takes out 2000× 1/4=500 bags.

Then at this time A has 2000-500= 1500 bags.

B There used to be 1500-500= 1000 bags.

A There were 2,000 bags.