How do I do this question

Refer to interactive solution 17.45 to review a method by which this problem can be solved. the fundamental frequencies of two air columns are the same. column a is open at both ends, while column b is open at only one end. the length of column a is 0.504 m. what is the length of column b?

Three times the sum of a number and seven is negative thirty-six. what is the number?

Which inequality has a dashed boundary line when graphed ?