Types of Variables in Equations Quick Check 3 of 53 of 5 Items Question Investigate the unknown values in the equation x+y=9 . Which of the following statements must be true?(1 point) Responses Both x and y can be negative values. Both x and y can be negative values. Both x and y must be positive values. Both x and y must be positive values. There are infinitely many solutions to this equation. There are infinitely many solutions to this equation. There is only one solution: x=4 and y=5.
