Answer:
Explanation:
 A) 
SELECT MECHNAME,AGE FROM MECHANIC;
 B) 
SELECT AIRNAME,SIZE FROM AIRPORT WHERE SIZE>=20 AND STATE='CALIFORNIA' AND YEAROPENED >=1935 ORDER BY SIZE ASC;
C) 
SELECT AIRNAME,SIZE FROM AIRPORT WHERE (SIZE>=20 OR YEAROPENED >=1935) AND STATE='CALIFORNIA';
D) 
SELECT AVG(SIZE) FROM AIRPORT WHERE STATE='CALIFORNIA' AND YEAROPENED >=1935;
 E)
 SELECT COUNT(AIRNAME) FROM AIRPORT WHERE STATE='CALIFORNIA' AND YEAROPENED >=1935;
 F) 
SELECT COUNT(AIRNAME),STATE FROM AIRPORT WHERE YEAROPENED>=1935 GROUP BY STATE;
 G) 
SELECT COUNT(AIRNAME),STATE FROM AIRPORT WHERE YEAR OPENED>=1935 GROUP BY STATE HAVING COUNT(*)>=5;
 H)
 SELECT MECHNAME FROM MECHANIC A JOIN AIRPORT B
ON A.AIRNAME=B.AIRNAME AND B.STATE='CALIFORNIA';
 I)   
SELECT MECHNAME FROM MECHANIC A
JOIN QUALIFICATION B
ON A.MECHNUM=B.MECHNUM
AND B.PROFRATE=4
JOIN SKILL C
ON B.SKILLNUM=C.SKILLNUM
AND SKILLNAME='FAN BLADE RELACEMENT';
 J)  SELECT MECHNAME FROM MECHANIC A
JOIN QUALIFICATION B
ON A.MECHNUM=B.MECHNUM
AND B.PROFRATE=4
JOIN SKILL C
ON B.SKILLNUM=C.SKILLNUM
AND SKILL NAME='FAN BLADE REPLACEMENT'
JOIN AIRPORT D
ON A.AIRNAME=D.AIRNAME
AND STATE='CALIFORNIA';
 K)   SELECT SUM(SALARY),CITY FROM MECHANIC A
JOIN AIRPORT B
ON A.AIRNAME=B.AIRNAME
AND STATE='CALIFORNIA'
GROUP BY CITY;
 L)   SELECT MAX(SIZE) FROM AIRPORT ;
 M)  SELECT MAX(SIZE) FROM AIRPORT WHERE STATE='CALIFORNIA';