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

### Instruction:
 Alama ya Bryan kwenye mtihani wa hesabu ni 20. Jen alipata alama 10 zaidi ya Bryan wakati Sammy alipata alama 2 chini ya Jen. Ikiwa mtihani wa hesabu una jumla ya alama 35, Sammy alifanya makosa mangapi?


### Response:
 Jen alipata alama 20 + 10 = <<20+10=30>>30 kwenye mtihani.
Sammy alipata alama mbili chini, hivyo alama yake ilikuwa 30 - 2 = <<30-2=28>>28.
Hivyo, Sammy alifanya makosa 35 - 28 = <<35-28=7>>7.