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

### Instruction:
Tatuya, Ivanna, and Dorothy took a quiz together. Tatuya scored twice as much as Ivanna, and Ivanna scored 3/5 times as many marks as Dorothy. If Dorothy scored 90 marks, calculate the average marks scored by the three.

### Response:
 Kwa kuwa Dorothy alipata alama 90, na Ivanna alipata 3/5 ya alama hizo, Ivanna alipata 3/5*90 = <<90*3/5=54>>54 alama.
Pamoja, Dorothy na Ivanna walipata jumla ya alama 54+90 = <<54+90=144>>144.
Tatuya alipata alama mara mbili ya Ivanna, hivyo alipata 2*54 = <<2*54=108>>108 alama.
Jumla ya alama walizopata watatu hao ni 108+144 = <<108+144=252>>252.
Hesabu wastani wa alama kwa watatu hao ni 252/3 = <<252/3=84>>84 alama.