Answer:
In December, Zalma will have $480.
Step-by-step explanation:
The time from March to October is 7 months. In those 7 months, she gains $280. So every month, her investment gains $40.
The time from March to December is 9 months. She will gain $360 during that time. We add her initial $120 with the $360, and Zalma will have $480.
It's not confirmed, but it's what I got. :D
