maths puzzle

12345678
Across
  1. 3. a symbol that doesn't have a fixed value
  2. 6. a number that is multiplied by a variable in an expression
  3. 7. it is the constant value of the ratio between two proportional quantities
  4. 8. a fixed numerical value
Down
  1. 1. the relation between two quantities of the same kind.
  2. 2. if an increase in one leads to a decrease in the other or vice versa
  3. 4. the reverse of factorization
  4. 5. a ratio that compares two quantities with different units.