Marta is correct because it has an equal sign, in which 'equa'tions have. An expression in the other hand doesn't have an equal sign.
This here, you don't necessarily include in your answer, it's just to further your understanding: Expression: 50m+12j Equation: 6+4x=18 Hope this helps
Sample Response: Marta is correct. This is an equation. The statement includes an equal sign. Equations include an equal sign, expressions do not include an equal sign.