That depends on the food!
For Lasagna, I'd say a 3x4 cut grid is a good size-- so 12 servings.
For something like baked ziti, spaghetti, or other main-course casserole you scoop with a spoon, it is 8-10.
For a side-dish casserole like potatoes, creamed corn or spinach, people will take less per serving, so plan on 16.
Finally, for something like broccoli or cauliflower where the serving size is determined by the cuts, you should cut the food into appropriate sizes for your guests and then simply count how many you can fit in the dish.
12 to 16 depending on how large you cut them...
a 9 x 13= 117 sq inches; if each serving is 3 x 3 inch you can get 117/9 = 13 servings
24 six ounce servings.
117
You should get six 4x4 servings with a a 1x9 on the bottom ans a 1x13 on the side left over. So, basically 7 servings.
The answer depends on the measurement units used and also on how large the helpings are.
It is: 13/9 = 1 and 4/9 as a mixed number
13/9 is 1 4/9 as a mixed number.
The mixed number equivalent to 13 over 9 is 14/9
9 and 13
13/9 = 1 and 4/9
9 inches x 9 inches = 81 one inch servings