Question 257247
Let x amount of time needed for B to do the job and 2x =amount of time for A
Then B works at the rate of 1/x job per day
And A works at the rate of 1/2x job per day

A & B together work at the rate of 1/4 job per day
So our equation to solve is:
1/x + 1/2x =1/4 multiply each term by 4x
4+2=x
x=6 hours---------------amount of time needed for B to do the job
2x=2*6=12 hours amount of time needed for A to do the job

CK
1/6 +1/12=1/4
2/12 + 1/12=1/4
3/12=1/4
1/4=1/4

Hope this helps ------ptaylor