1. Stating the problem: Convert and subtract the quantities given in different time units and express the result in decades. 2. Understand the units: - 1 abad (century) = 10 dekad (decades) - 1 dekad = 1 dekad (same unit) 3. Convert 1.5 abad to dekad: $$1.5 \text{ abad} = 1.5 \times 10 = 15 \text{ dekad}$$ 4. Convert mixed number 5 1/5 dekad to improper fraction: $$5 \frac{1}{5} = \frac{5 \times 5 + 1}{5} = \frac{26}{5} = 5.2 \text{ dekad}$$ 5. Perform the subtraction: $$15 - 5.2 = 9.8 \text{ dekad}$$ 6. Final answer: The result is **9.8 dekad**.