Answer:
she worked 9 hours at sporting goods store and 6 hours on piano lessons.
Step-by-step explanation:
total hours=15
8.47x + 17(15-x) = 178.23
8.47x + 225 - 17x = 178.23
225 - 178.23 = 17x - 8.47x
76.77 = 8.53x
x = 76.77 / 8.53
x = 9
therefore she worked 9 hours at sporting goods centre and the remaining hours (15-9) giving piano lessons.
Answer:
D
Step-by-step explanation:
H+ is the hydrogen ion concentration.
This problem requires the use of solving log equation.
PH of vinegar is 2.9, lets find the number of hydrogen ions in it by using the equation:
![PH=-Log[H^{+}]\\2.9=-Log[H^+]\\-2.9=Log_{10}[H^+]](https://tex.z-dn.net/?f=PH%3D-Log%5BH%5E%7B%2B%7D%5D%5C%5C2.9%3D-Log%5BH%5E%2B%5D%5C%5C-2.9%3DLog_%7B10%7D%5BH%5E%2B%5D)
Note: Log is normally base 10 if not specified
Now, to solve, we use exponential to log conversion formula shown below:

Now lets solve:
![-2.9=Log_{10}[H^+]\\H^+=10^{-2.9}\\H^+=0.001259](https://tex.z-dn.net/?f=-2.9%3DLog_%7B10%7D%5BH%5E%2B%5D%5C%5CH%5E%2B%3D10%5E%7B-2.9%7D%5C%5CH%5E%2B%3D0.001259)
Now, the PH of milk is 6.6, so we follow same procedure and find the number of hydrogen ion in milk. Shown below:
![PH=-Log[H^{+}]\\6.6=-Log[H^+]\\-6.6=Log_{10}[H^+]\\H^+=10^{-6.6}\\H^+=0.0000002512](https://tex.z-dn.net/?f=PH%3D-Log%5BH%5E%7B%2B%7D%5D%5C%5C6.6%3D-Log%5BH%5E%2B%5D%5C%5C-6.6%3DLog_%7B10%7D%5BH%5E%2B%5D%5C%5CH%5E%2B%3D10%5E%7B-6.6%7D%5C%5CH%5E%2B%3D0.0000002512)
So, to find how many times it is greater, we divide first answer we found by the second answer:

That is about 5000 times, answer D is right.
Answer:
20 -> 5
Step-by-step explanation:
20 / 4 = 5
40 -> 10
160 -> 40
Answer:
7
Step-by-step explanation:
I made this guess based on the amount of points offered.
That's a hard one, good luck