Math crossword puzzle

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Across
  1. 1. 1 6/7-2+1
  2. 4. 1/10+-2/3
  3. 6. -4+4+9/10
  4. 7. 1/3+-7/10
  5. 9. 1/6+-5/6
Down
  1. 1. -2+2 6/10
  2. 2. 2-3/5+1/5
  3. 3. -3+4/5+3
  4. 4. 1/10+-1/3
  5. 5. -1/3+3/7
  6. 7. 3-4+1/9
  7. 8. 7+-6 2/5