Hector's banana bread recipe requires $$2 \frac {3}{4}$$ cups of flour, and he has already added $$\frac {2}{3}$$ cups of flour. The amount of flour Hector still needs to add, can be written as $$\frac {a}{b}$$, where $$a$$ and $$b$$ are coprime positive integers. What is the value of $$a+b$$?