The function will be

where y is the balance, and x is the number of month.
The raph will be a line on the xy-plain which starts at the point (0, 360), and end in the point (72, 0).
Hope it helps.
Answer:
b and E and c
Step-by-step explanation:
- A is false because some elements have the same image like 2.3 and 2.2 , 2.5 ...
- B is true because the image of an integer remains the same using the greatest integer function. So C is true
- E is true
The answer is the first one