SOLUTION: please help me solve this problem: 1. working together two men can do a painting job in 20 days. working alone one man would take 9 days longer than the other to complete the job

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Question 678789: please help me solve this problem:
1. working together two men can do a painting job in 20 days. working alone one man would take 9 days longer than the other to complete the job. how long would it take each separately?

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

Let
A+= number of days Painter A can do the job
B+= number of days Painter B can do the job
Working together,
1%2FA+%2B+1%2FB+=+1%2F20............ equation 1
ASSUMING that it takes Painter A 9 more days to do the job alone than Painter B, then
A+=+B+%2B+9
and substituting this into equation 1,
1%2F%28B+%2B+9%29+%2B+1%2FB+=+1%2F20
Multiplying both sides by B%28B+%2B+9%29,
B+%2B+%28B+%2B+9%29+=+B%28B+%2B+9%29%2F20.......multiplying both sides by 20
2B+%2B+9+=+B%28B+%2B+9%29%2F20
40B+%2B+180+=+B%5E2+%2B+9B
Rearranging,
B%5E2+-+31B+-+180+=+0
Factoring the above,
%28B+-+36%29%28B+%2B+5%29+=+0
Solving for B,
B+=+36 and B+=+-5
and ignoring the negative root,
B+=+36
and solving for A,
A+=+9+%2B+36
A+=+45
ANSWER:
Painter A can do the job alone in 45 days
and
Painter+B can do the job alone in 36 days.