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

### Instruction:
Jacob takes four tests in his physics class and earns 85, 79, 92 and 84. What must he earn on his fifth and final test to have an overall average of 85?

### Response:
 Kwa kuwa anahitaji wastani wa alama 85 na anafanya mitihani mitano, anapaswa kuwa na jumla ya alama 85 * 5 = <<85*5=425>>425.
Kwa sasa ana alama 85 + 79 + 92 + 84 = <<85+79+92+84=340>>340.
Hivyo, kwenye mtihani wake wa tano anahitaji alama 425 - 340 = <<425-340=85>>85.