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

### Instruction:
Kevin is a fruit vendor. He always sells a total of 50 crates of fruit per week. Last week he sold 13 crates of grapes, 20 crates of mangoes, and the rest were passion fruits. How many passion fruit crates did he sell?

### Response:
 Kati ya zabibu na embe, tuna masanduku 13+20 = <<13+20=33>>33.
Masanduku yaliyobaki ni ya mapera, hivyo tuna masanduku 50-33=<<50-33=17>>17 ya mapera.