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

### Instruction:
Bryan's score on a math exam is 20. Jen scored 10 more than Bryan while Sammy scored 2 fewer than Jen. If the math exam has 35 points in all, how many mistakes did Sammy make?

### Response:
Jen scored 20 + 10 = <<20+10=30>>30 on the exam.
Sammy scored two less, so his score was 30 - 2 = <<30-2=28>>28
He made 35 - 28 = <<35-28=7>>7 mistakes.
#### 7