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

### Instruction:
Melly's two cats each have litters of kittens at the same time. The first cat has 3 blue-eyed kittens and 7 brown-eyed kittens. The second cat has 4 blue-eyed kittens and 6 brown-eyed kittens. What percentage of all the kittens have blue eyes?

### Response:
The total number of blue-eyed kittens is 3 + 4 = <<3+4=7>>7.
The total number of brown-eyed kittens is 7 + 6 = <<7+6=13>>13.
The total number of kittens is 7 + 13 = <<7+13=20>>20.
The percentage of blue-eyed kittens is 7/20 * 100% = 35%.
#### 35