Math Spelling Numbers

123456789
Across
  1. 3. 6+7
  2. 5. a dozen
  3. 6. 16+3
  4. 7. 20-4
  5. 9. 11+6
Down
  1. 1. 18-3
  2. 2. 10+4
  3. 4. 7+4
  4. 8. 8+8