Answer:
The computer would be worth $25 after 4 years.
General Formulas and Concepts:
Algebra II
Exponential Function Formula:

- a is the initial amount
- b is the ratio
- x is the amount of time
Explanation:
Step 1: Define
Identify given.
a = $400
b = 0.5
x = 4 years
Step 2: Find
- [Exponential Function Formula] Substitute in variables:

- Evaluate:

∴ the computer's depreciated value over 4 years would sum up to $25.
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Topic: Algebra II