1. **Stating the problem:** We need to subtract the numbers represented on the abacus rods: Hundreds (H), Tens (T), and Units (U). 2. **Given values:** - Hundreds: 7 beads - 5 beads - Tens: 5 beads - 2 beads - Units: 6 beads - 5 beads 3. **Formula used:** Subtraction is done digit by digit: $$\text{Result} = (H_1 - H_2) \times 100 + (T_1 - T_2) \times 10 + (U_1 - U_2)$$ 4. **Calculations:** - Hundreds: $7 - 5 = 2$ - Tens: $5 - 2 = 3$ - Units: $6 - 5 = 1$ 5. **Combine the results:** $$2 \times 100 + 3 \times 10 + 1 = 200 + 30 + 1 = 231$$ 6. **Explanation:** Each rod represents a place value. Subtracting beads on each rod gives the digit for that place. Combining these digits forms the final number. **Final answer:** $231$