Below is an instruction that describes a task. Write a response that appropriately completes the request in Chinese. Please answer in Chinese.

### Instruction:
 约翰买了10包魔术卡牌。每包有20张卡牌，其中1/4是非常见的。他得到了多少非常见的卡牌？


### Response:
 每包有20/4 = <<20/4=5>>5张非常见的卡牌
所以他得到了10*5 = <<10*5=50>>50张非常见的卡牌