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

### Instruction:
Sam has 18 cows.  5 more than half the cows are black.  How many cows are not black?

### Response:
Let b be the number of black cows and w be the number of non-black cows. We know that b + w = 18, b = 5 + w/2 and b - w/2 = 5.
Substituting the second equation into the third equation, we get 5 + w/2 - w/2 = 5
Combining like terms, we get 5 + 0 = 5
5 = 5
#### 5

