math crossword puzzle

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Across
  1. 2. algebra
  2. 4. coordinate plane lines meet
  3. 7. number
  4. 8. the value of a number
  5. 10. the difference
  6. 11. number standing alone
  7. 12. letter
Down
  1. 1. sequence
  2. 3. equation without equal sign
  3. 5. number with letter
  4. 6. the angle a line is going on a coordinate plane
  5. 9. problem