1. A string vibrates at its natural frequency of 300 Hz. (a) Calculate the new natural frequency when the tension is increased by 5% without
altering the length.
(b) A second string has the same tension as the original string but twice the mass
per unit length. Calculate the natural frequency of the second string.​

see earlier

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)

option number c is the right answer.