When two teams A and B work together, it takes 18 days to complete a job. After team A works for 3 days, and Team B works for 4 days, only 1/5 of the job is done. How long does it take for Team A to complete the job alone? How long does it take for Team B to complete the job alone?
Whats the equation for the first sentence? I know the second one is
$3A+4B=1/5W$
when A is the speed of A, B is the speed of B, and W is the amount of work completed.
Answer
Now that I know...
$18A+18B=1$
$15A+20B=1$(multiplied by 5)
Substition, so it becomes
$18A+18B=15A+20B$
Then it becomes $3A=2B$, making B 1.5 times faster than A.
You can substitute B for 3 and A for 2 now.
$54+36=90$, so $90/3=30$ days for B and $90/2=45$ days for A.
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