Need help on HS geometry

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?

Empty box + box + empty box fill in the box is equal to 30 how

If f(x)=x+7 and g(x)=1/x what is (fog)(x)