dv graves ให้บริการได้นานแค่ไหนเมื่อเทียบกับ jf jenkins ?ไม่จำเป็นต้องใช้ตารางทั้งหมด
how many more years did d. v. graves serve compared to j. f. jenkins ?It is not neccessary to use all the tables.
 table_203_577:  id [ number]  "tenure" [ text]  "coach" [ text]  "years" [ number]  "record" [ text]  "pct." [ number] 
SELECT (SELECT "years" FROM table_203_577 WHERE "coach" = 'd. v. graves') - (SELECT "years" FROM table_203_577 WHERE "coach" = 'j. f. jenkins')