### Database Schema:
CREATE TABLE Demog (
	GEOID	INTEGER	NULL	PRIMARY KEY,
	INHABITANTS_K	REAL	NULL,
	INCOME_K	REAL	NULL,
	A_VAR1	REAL	NULL,
	A_VAR2	REAL	NULL,
	A_VAR3	REAL	NULL,
	A_VAR4	REAL	NULL,
	A_VAR5	REAL	NULL,
	A_VAR6	REAL	NULL,
	A_VAR7	REAL	NULL,
	A_VAR8	REAL	NULL,
	A_VAR9	REAL	NULL,
	A_VAR10	REAL	NULL,
	A_VAR11	REAL	NULL,
	A_VAR12	REAL	NULL,
	A_VAR13	REAL	NULL,
	A_VAR14	REAL	NULL,
	A_VAR15	REAL	NULL,
	A_VAR16	REAL	NULL,
	A_VAR17	REAL	NULL,
	A_VAR18	REAL	NULL
);

CREATE TABLE Sales (
	EVENTID	INTEGER	NULL	PRIMARY KEY,
	REFID	INTEGER	NULL,
	EVENT_DATE	DATETIME	NULL,
	AMOUNT	REAL	NULL,
	foreign key (REFID) references Customers (ID)
);

CREATE TABLE mailings3 (
	REFID	INTEGER	NULL	PRIMARY KEY,
	REF_DATE	DATETIME	NULL,
	RESPONSE	TEXT	NULL
);

CREATE TABLE Mailings1_2 (
	REFID	INTEGER	NULL	PRIMARY KEY,
	REF_DATE	DATETIME	NULL,
	RESPONSE	TEXT	NULL,
	foreign key (REFID) references Customers (ID)
);

CREATE TABLE Customers (
	ID	INTEGER	NULL	PRIMARY KEY,
	SEX	TEXT	NULL,
	MARITAL_STATUS	TEXT	NULL,
	GEOID	INTEGER	NULL,
	EDUCATIONNUM	INTEGER	NULL,
	OCCUPATION	TEXT	NULL,
	age	INTEGER	NULL,
	foreign key (GEOID) references Demog (GEOID)
);

### User's Query:
List the educationnum and response of customers within the age of 20 to 30 that has the highest number of inhabitants among the group.

### Extra Knowledge:
age of 20 to 30 refers to age BETWEEN 20 AND 30; the highest number of inhabitants refers to MAX(INHABITANTS_K);
SELECT T1.EDUCATIONNUM, T2.RESPONSE FROM Customers AS T1 INNER JOIN Mailings1_2 AS T2 ON T1.ID = T2.REFID INNER JOIN Demog AS T3 ON T1.GEOID = T3.GEOID WHERE T1.age >= 20 AND T1.age <= 30 ORDER BY T3.INHABITANTS_K DESC LIMIT 1