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

### Instruction:
 Marcus alikuwa na mawe 18. Aliyapiga nusu yake juu ya ziwa, lakini Freddy alimpa mawe mengine 30. Marcus ana mawe mangapi sasa?


### Response:
 Marcus alikuwa na mawe 18/2 = <<18/2=9>>9 yaliyosalia.
Baada ya Freddy kumpa zaidi, ana mawe 9 + 30 = <<9+30=39>>39 sasa.