What is Algebra?

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Across
  1. 2. a mathematical sentence (think equal sign)
  2. 4. answer to a multiplication problem
  3. 5. answer to an addition problem
  4. 8. branch of mathematics that describes general relationships between quantities
  5. 9. symbol that represents a quantity
Down
  1. 1. answer to subtraction problem
  2. 2. a mathematical phrase
  3. 3. answer to a division problem
  4. 6. symbol that represents a number
  5. 7. small numbers multiplied to create a product