30.(2023•新城区校级模拟)在平行四边形ABCDABCDABCD中,GGG为ΔBCD\Delta BCDΔBCD的重心,AG→=xAB→+yAD→\overrightarrow{AG}=x\overrightarrow{AB}+y\overrightarrow{AD}AG=xAB+yAD,则3x+y=3x+y=3x+y=___83\frac{8}{3}38___.