On a moonless night, three fireflies danced in the evening breeze.  They were joined by four less than a dozen more fireflies, before two of the fireflies flew away.  How many fireflies remained?
Four less than a dozen is 12-4=<T>subtract(12, 4)=8
The three fireflies were joined by four less than a dozen more fireflies, for a total of 3+8=<T>add(3, 8)=11 fireflies.
Two flew away, leaving 11-2=<T>subtract(11, 2)=9 fireflies remaining.
