what was the difference between her qualifying scores for balance beam between boston and philadelphia ?
CREATE TABLE table_204_975 (
    id number,
    "year" number,
    "competition" text,
    "location" text,
    "event" text,
    "final-rank" text,
    "final-score" number,
    "qualifying rank" number,
    "qualifying score" number
)
SELECT ABS((SELECT "qualifying score" FROM table_204_975 WHERE "event" = 'balance beam' AND "location" = 'boston') - (SELECT "qualifying score" FROM table_204_975 WHERE "event" = 'balance beam' AND "location" = 'philadelphia'))
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: what was the difference between her qualifying scores for balance beam between boston and philadelphia ? ### Input: CREATE TABLE table_204_975 (
    id number,
    "year" number,
    "competition" text,
    "location" text,
    "event" text,
    "final-rank" text,
    "final-score" number,
    "qualifying rank" number,
    "qualifying score" number
) ### Response: SELECT ABS((SELECT "qualifying score" FROM table_204_975 WHERE "event" = 'balance beam' AND "location" = 'boston') - (SELECT "qualifying score" FROM table_204_975 WHERE "event" = 'balance beam' AND "location" = 'philadelphia'))