The frequency of the wave is 0.4 Hz. Calculate the period.

use the formula

Explanation:

F = 1/T

where F = frequency and T = period

so put 0.4 Hz into the frequency

0.4 =1/T

T = 2.5 seconds

hope this helps

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.)