1. Problem (a): Compute the sum $$360 - 357 + 354 - 351 + \cdots + 300 - 297$$. 2. This is an arithmetic series with alternating signs, decreasing by 3 each time. 3. Group terms in pairs: $$(360 - 357) + (354 - 351) + \cdots + (300 - 297)$$. 4. Each pair equals $3$ because $360 - 357 = 3$, $354 - 351 = 3$, etc. 5. Count the number of pairs: from 360 down to 297 in steps of 6 (since each pair covers two terms, each decreasing by 3). 6. Number of terms: $$\frac{360 - 297}{3} + 1 = 21 + 1 = 22$$ terms. 7. Number of pairs: $$\frac{22}{2} = 11$$ pairs. 8. Sum: $$11 \times 3 = 33$$. 9. Problem (b): Compute $$2006 - 1 - 2 - 3 - \cdots - 48 - 49 - 50$$. 10. Sum of numbers from 1 to 50: $$\frac{50 \times 51}{2} = 1275$$. 11. Result: $$2006 - 1275 = 731$$. 12. Problem (c): Compute $$280 - 276 + 272 - 268 + \cdots + 200 - 196$$. 13. Group terms in pairs: $$(280 - 276) + (272 - 268) + \cdots + (200 - 196)$$. 14. Each pair equals $4$. 15. Count pairs: from 280 down to 196 in steps of 8 (each pair covers two terms decreasing by 4). 16. Number of terms: $$\frac{280 - 196}{4} + 1 = 21 + 1 = 22$$ terms. 17. Number of pairs: $$\frac{22}{2} = 11$$ pairs. 18. Sum: $$11 \times 4 = 44$$. Final answers: (a) 33 (b) 731 (c) 44