Denver has 7/19 of the dog food so the rest of the (I’m assuming dogs) have the remaining portion, 12/19
Engle and Fido have to split 12/19 into a ratio of 7:4
So... 12/19 has to split into 11 sectors of 1 representing 7:4
If Fido has 4 of the amount of food than
12 * 4 / 19 * 11 = 0.229665, 23%
Fido’s share is 23%