Question

Your new computer cost $1500 but it depreciates in value by about 18% each year, how long will it take before your computer is worth $50?

Answer 1

1. What is 18%? 1500 * .18 = 270
2. Write the equation. 1500 - 270(x) = 50
3. Single out your X by subtracting 1500 from both sides. -250x = -1450
4. X still isn't singled out. Divide by -250. x = 1450/270 (two negatives produce a positive).
5. Simplify. x = 145/27 (fraction), 5.370370 (decimal)

Assuming 18% each year is constant through the months (say, 1.5% decrease each month), your computer will be worth $50 around 5.4 (rounded) years.