Answer:
4.50
Step-by-step explanation:
i hope i got it correct i'm in middle school
Given that,
y varies directly with x and y = 10 when x = 20.
To find,
The value of y when x = 15.
Solution,

Put x = 20 and y = 10

Put k = 1/2 and x = 15 to find the value of y.

So, the value of y is 7.5
Answer: Wavelength is the distance between sound waves while frequency is the number of times in which the sound wave occurs.
Step-by-step explanation: