All four operations with fractions and negatives

Give the answer as a fraction in lowest terms, or a whole number.

1. Evaluate: −1/2 + (−1/2) (Write a fraction in lowest terms, or a whole number.)
2. Evaluate: −1/2 + 4/5 (Write a fraction in lowest terms, or a whole number.)
3. Evaluate: 1/2 + 3/5 (Write a fraction in lowest terms, or a whole number.)
4. Evaluate: −1/2 − (−3/8) (Write a fraction in lowest terms, or a whole number.)
5. Evaluate: 1/3 × (−1/2) (Write a fraction in lowest terms, or a whole number.)
6. Evaluate: 1/2 − (−7/8) (Write a fraction in lowest terms, or a whole number.)
7. Evaluate: 1/4 − 9/10 (Write a fraction in lowest terms, or a whole number.)
8. Evaluate: 5/8 + (−1/2) (Write a fraction in lowest terms, or a whole number.)
9. Evaluate: 2/7 + (−1/3) (Write a fraction in lowest terms, or a whole number.)
10. Evaluate: −1/2 − (−1/2) (Write a fraction in lowest terms, or a whole number.)
11. Evaluate: 3/8 × 1/2 (Write a fraction in lowest terms, or a whole number.)
12. Evaluate: 8/9 + (−3/10) (Write a fraction in lowest terms, or a whole number.)
13. Evaluate: −1/4 ÷ 5/6 (Write a fraction in lowest terms, or a whole number.)
14. Evaluate: −2/3 − (−5/9) (Write a fraction in lowest terms, or a whole number.)
15. Evaluate: −4/7 ÷ (−1/2) (Write a fraction in lowest terms, or a whole number.)
16. Evaluate: −1/2 × 2/3 (Write a fraction in lowest terms, or a whole number.)
17. Evaluate: −1/7 ÷ (−1/3) (Write a fraction in lowest terms, or a whole number.)
18. Evaluate: −4/5 ÷ (−1/3) (Write a fraction in lowest terms, or a whole number.)
19. Evaluate: 1/12 × 2/3 (Write a fraction in lowest terms, or a whole number.)
20. Evaluate: 1/3 × 1/4 (Write a fraction in lowest terms, or a whole number.)