Answer:
- 100 calendars and 150 posters 
Explanation:
- Note it seem the "$" shouldn't be in front of 250 as it is the numbe of items
a) The second equation is
b) The graph of both equations is attached 
The intersection point of the lines is (100, 150)
It indicates 100 calendars and 150 posters to be donated to meet both of targets $600 and 250 items.