SOLUTION: X and Y can assemble machine parts together in 30 days. They started work and Y left work after 20 days. X assemnled the remaining machine parts in 20 days. In how many days X can

Algebra ->  Test -> SOLUTION: X and Y can assemble machine parts together in 30 days. They started work and Y left work after 20 days. X assemnled the remaining machine parts in 20 days. In how many days X can       Log On


   

Question 1184804: X and Y can assemble machine parts together in 30 days. They started work and Y left work after 20 days. X assemnled the remaining machine parts in 20 days. In how many days X can assemble machine parts by himself?
Answer by josgarithmetic(39626) About Me  (Show Source):
You can put this solution on YOUR website!
1%2Fx%2B1%2Fy=1%2F30
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20%281%2Fx%2B1%2Fy%29%2B20%281%2Fx%29=1
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system%281%2Fx%2B1%2Fy=1%2F30%2C2%2Fx%2B1%2Fy=1%2F20%29

Equations might be easier to handle if a substitution is made:
u=1%2Fx and v=1%2Fy

system%28u%2Bv=1%2F30%2C2u%2Bv=1%2F20%29
Elimination Method should be easier this way.
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E2-E1:
u=1%2F20-1%2F30
u=3%2F60-2%2F60
u=1%2F60
Back-substituting, 1%2Fx=1%2F60------------highlight%28x=60%29
and you can solve for y whatever way you want.