SOLUTION: 2 men can do the same amount of work that 3 boys can do. 4 men and 10 boys can do a piece of work in 21 days. how many days will 6 men and 15 boys do the work?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: 2 men can do the same amount of work that 3 boys can do. 4 men and 10 boys can do a piece of work in 21 days. how many days will 6 men and 15 boys do the work?      Log On


   

Question 981125: 2 men can do the same amount of work that 3 boys can do. 4 men and 10 boys can do a piece of work in 21 days. how many days will 6 men and 15 boys do the work?
Answer by josgarithmetic(39615) About Me  (Show Source):
You can put this solution on YOUR website!
Uniform Work Rates, RT=J, amount of job.

R for rate of one man;
r for rate of one boy;
Rates of workers doing the job at the same time as a team work at
the sum of their individual rates.

system%282R=3r%2C%284R%2B10r%2921=1%2C%286R%2B15r%29t=1%29
This is three equations for a system in three unknown variables.
Your final result desired is the value for t;
and finding R and r along the way is good to do.


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Best method is use the first two equations to solve for R and r; and then use the values to solve for t in the third equation.