Tom can paint the fence in 12 hours, but if he works together with a friend they can finish the job in 8 hours. how long would it take for his friend to paint this fence alone?

It takes his friend 24 hours

Step-by-step explanation:

The formula for time on a job is

1/A + 1/B = 1/C

where A is the time for person A

B is the time for person B

C is the time for A and B together

Tom is person A and his friend is person B

1/12 + 1/B = 1/8

The Common denominator is 24, so multiply by 24 on each side

24(1/12 + 1/B) = 1/8*24

2 +24/B = 3

Subtract 2 from each side

2-2 +24/B = 3-2

24/B =1

Multiply each side by B

24/B *B = B*1

24 = B

answer 1 : option "c"

answer 2 : option "d"

answer 3 : option "b"

answer 4 : option "d"

answer 5 : option "b"

answer 6 : option "a"

answer 7 : option "c"

answer 8 : option "d"

answer 9 : option "c"

answer 10 : option "d"

answer 11 : option "c"

answer 12 option "b"

answer 13 option "c"

answer 14 option "c"

answer 15 option "d"

answer 16 option "a"

answer 17 option "b"

answer 18 option "c"

answer 19 option "a"

answer 20 option "a"

answer 21 option "c"

d