SOLUTION: A and B can do a work in 12 days and 20 days.A works alone for 4 days and then B joins to help.in how many days will they finish the job? ans- A in 1 day = 1/12 B in 1 day

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A and B can do a work in 12 days and 20 days.A works alone for 4 days and then B joins to help.in how many days will they finish the job? ans- A in 1 day = 1/12 B in 1 day      Log On


   



Question 948826: A and B can do a work in 12 days and 20 days.A works alone for 4 days and then B joins to help.in how many days will they finish the job?
ans- A in 1 day = 1/12
B in 1 day = 1/20
A alone works for 4 days
therefore in 4 days A'work = 4*1/20= 1/5
Remaining work 4/5
then B joins......

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
You made a mistake.
A working for 4 days would be,
A%2A4=%281%2F12%294=1%2F3
So that leaves 2%2F3 to complete.
.
.
.
So then use the rate for A and B together.
A%2BB=1%2F12%2B1%2F20=5%2F60%2B3%2F60=8%2F60=2%2F15
So then,
%28A%2BB%29t=2%2F3
%282%2F15%29t=2%2F3
t=5 days