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

### Instruction:
Louie obtained 80% on a math quiz. He had 5 mistakes. How many items were there on the math quiz?

### Response:
Louie got 100% - 80% = 20% of the total items incorrect, which is equal to 5 items.
So 1% is equal to 5/20 = <<5/20=0.25>>0.25 items.
Hence, there were 0.25 x 100 = <<0.25*100=25>>25 items on the math quiz.
#### 25