When andrew and moe worked together last year, they painted a fence in 6 hours. the previous year, moe painted the fence by himself. the year before that, andrew painted by herself, but it took 9 hours longer. how long did it take andree to paint the fence? a. 9 hoursb. 6 hoursc. 18 hoursd. 12 hours

M = Moe's rate

a = Andrew's rate

we know both of them together can do the whole thing in 6 hours, so in 1 hour they have done 1/6 of the job.

since Moe can do the job by himself in "m" hours, in 1 hour he has done 1/m of it then, and whilst Andrew can do it in "a"  hours, in 1 hour he has done 1/a of it.

now, let's keep in mind that Andrew is slower, it took Andrew 9 hours longer than it took Moe, so if Moe took "m" hours, Andrew took "m + 9", so a = m + 9, and therefore Andrew in 1 hour has done 1/(m+9).



since it's a speed rate, it cannot be -6.

so, Moe can do the job by himself in 9 hours, well, Andrew can do it in, 9+9.

The third one obviously