The department store shipped 600 pairs of sports shoes, which were packed in 2 wooden cases and 6 cartons respectively. If two cartons contain as many sneakers as 1 wooden box,

Analysis: 300 pairs of sports shoes are packed in 2 wooden cases and 6 cartons respectively. If they are all packed in cartons or wooden cases, we can work out how many pairs can be packed in a carton or a wooden case. So the key to solve this problem is to change cartons into wooden cases according to the relationship between cartons and wooden cases. Because two cartons can hold as many as 1 wooden case, and two wooden cases can hold as many as four cartons. In this way, the number of shoes packed in two wooden cases and six cartons is as much as that packed in 10 cartons.

Carton: 300(2×2+6)= 30 (double), wooden case: 30×2=60 (double).