Ответ:

a)

  1. 1st — first
  2. 2nd — second
  3. 3rd — third
  4. 4th — fourth
  5. 5th — fifth
  6. 6th — sixth
  7. 7th — seventh
  8. 8th — eighth
  9. 9th — ninth
  10. 10th — tenth
  11. 11th — eleventh
  12. 12th — twelfth
  13. 13th — thirteenth
  14. 14th — fourteenth
  15. 15th — fifteenth
  16. 16th — sixteenth
  17. 17th — seventeenth
  18. 18th — eighteenth
  19. 19th — nineteenth
  20. 20th — twentieth

b)

  • 31st — thirty-first
  • 42nd — forty-second
  • 53rd — fifty-third
  • 64th — sixty-fourth
  • 118th — one hundred and eighteenth
  • 329th — three hundred and twenty-ninth
  • 40th — fortieth
  • 50th — fiftieth
  • 60th — sixtieth
  • 70th — seventieth
  • 80th — eightieth
  • 90th — ninetieth
  • 100th — one hundredth

Примеры словосочетаний: the 21st of September — the twenty-first of September; the 63rd birthday — the sixty-third birthday.