Question

Is the equation 3+z= -9 true false or open

Answer 1

Subtract 3 from both sides

(z = -9 - 3)

Simplify -9 - 3 to -12

z = -12

3 + -12 = -9 so this is true.

Answer 2

3+z = -9 is open since you do not have a value for z