4 cups equal 1 quart according to the US standards. Using that, we get an equation like: 4c = 1q if you want 12 cups, you have to multiply the left side by 3 meaning you would also have to multiply the right side by 3. 3(4c) = 3(1q) 12c = 4q you get 12 cups equals 4 quarts.
Since it must be an integer, 5 would make it up to the full length of the longest line. What you get is not quite a triangle. The way to get a triangle is to add one more to the 5 to make 6