In the figure, what is the area of triangle $abd$? express your answer as a common fraction. [asy] draw((34)); draw((0,,0)); ,,.,.5)); label("$a$",(0,4),w); label("2",(0,3),w); label("$e$",(0,2),w); label("2",(0,1),w); label("$c$",(0,0),sw); label("3",(1.5,0),s); label("$f$",(3,0),s); label("4",(5,0),s); label("$b$",(7,0),se); label("$d$",(21/11,16/11),ne); [/asy]