Answer:
720 ways
Explanation:
Generally, combination is expressed as;

The question consists of 9 multiple-choice questions and examinee must answer 7 of the multiple-choice questions.
⇒ ⁹C₇


= 36
The question consists of 6 open-ended problems and examinee must answer 3 of the open-ended problems.
⇒ ⁶C₃


= 20
Combining the two combinations to determine the number of ways the questions and problems be chosen if an examinee must answer 7 of the multiple-choice questions and 3 of the open-ended problem.
⁹C₇ × ⁶C₃
= 36 × 20
= 720 ways