Answer:
D
Step-by-step explanation:
loudness depends on the amplitude or height of the sound waves
Answer:
The solution is the point (18,0)
Step-by-step explanation:
we have
-----> equation A
-----> equation B
Solve the system by substitution
substitute equation B in equation A
![\frac{1}{3}x-6=-\frac{1}{3}x+6](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B3%7Dx-6%3D-%5Cfrac%7B1%7D%7B3%7Dx%2B6)
solve for x
Adds (1/3)x both sides
![\frac{1}{3}x-6+\frac{1}{3}x=6](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B3%7Dx-6%2B%5Cfrac%7B1%7D%7B3%7Dx%3D6)
![\frac{2}{3}x-6=6](https://tex.z-dn.net/?f=%5Cfrac%7B2%7D%7B3%7Dx-6%3D6)
Adds 6 both sides
![\frac{2}{3}x=6+6](https://tex.z-dn.net/?f=%5Cfrac%7B2%7D%7B3%7Dx%3D6%2B6)
![\frac{2}{3}x=12](https://tex.z-dn.net/?f=%5Cfrac%7B2%7D%7B3%7Dx%3D12)
![x=12(3)/2\\x=18](https://tex.z-dn.net/?f=x%3D12%283%29%2F2%5C%5Cx%3D18)
<em>Find the value of y</em>
substitute the value of x in equation A or equation B
![y=-\frac{1}{3}(18)+6=0](https://tex.z-dn.net/?f=y%3D-%5Cfrac%7B1%7D%7B3%7D%2818%29%2B6%3D0)
therefore
The solution is the point (18,0)
<span>If line m is parallel to line k, then it has a slope of C)2/3</span>
25% = 85 / 4 = $21.25 off
5% = 85 / 20 = $4.25
75% = 21.25 • 3 = $63.75
$63.75 + $4.25 = $68
Her total bill was $68