Answer:
C = 42/ 13 hours or 3 3/13 hours
Step-by-step explanation:
The formula is
1/A +1/B = 1/C
where A is the time for person 1 to do the job alone
B is the time for person B to do the job alone
C is the time for them to do the job together
1/6 + 1/7 = 1/C
The common denominator is 42C so multiply each side by 42C
42 C*(1/6 + 1/7) = 1/C *42C
Distribute
7C +6C = 42
13 C = 42
Divide each side by 13
C = 42/13
Changing to a mixed number
C = 3 3/13 hours
I believe you are asking in how many ways they can sit. If so:
The 1st can sit anywhere: he has only 1 way to sit
The 2nd can sit in 11 ways, since one seat is already occupied
The 3rd can sit in 10 ways, since 2 seat are already occupied
The 4th can sit in 9 ways, since 3 seat are already occupied
The 5th can sit in 8 ways, since 4 seat are already occupied
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The 12th can sit in 1 way, since11 seat are already occupied
General formula for a circular table:
Number of ways they n persons can be seated: (n-1)!
and the 12 can be seated in (12-1)! = 11! = 39,916,800 ways.
This is called circular permutation
Answer:
f(-3)=5x^2+5x*3
-f*3=5x^2+5*3x
-3f=5x^2+15x
f=-5x(x+3)/3
f(-9)=5x^2+5x*3
-f*9=5x^2+5*3x
-9f=5x^2+15x
f=-5x(x+3)/9
Step-by-step explanation:
hope it helps you?
Answer:
-12
Step-by-step explanation:
i think this is right