有蜘蛛、蜻蜓、蝉三种动物共18只,共有腿118条,翅膀20对(蜘蛛8条腿;蜻蜓6条腿,两对翅膀;蝉6条腿,一对翅膀),求蜻蜓有多少只?)|+~3c7m,b:W5H5l5}*F*H
算式:提示-I7y2x3B2y:v-[0v4n)|+~3c7m,b:W5H5l5}*F*H
答:蜻蜒有6v9T8N-e只。)|+~3c7m,b:W5H5l5}*F*H