Gentry poured 23.5 ounces of milk and 7.75 ounces of cream in a mixing bowl.
how much more cream could gentry add to the bowl if the capacity of the bowl is 35.5 ounces?

Notice that because the capacity of the bowl is 35.5 ounces, but there has already been 31.25 ounces total added to it (23.5 ounces + 7.75 ounces), all that needs to be done is subtract 31.25 from 35.5:
35.5 - 31.25 = 4.25 ounces of cream could be added