SOLUTION: If 4 men or 7 boys can do a work in 29 days, then 12 men and 8 boys will do the same work in?

Algebra ->  Numeric Fractions Calculators, Lesson and Practice -> SOLUTION: If 4 men or 7 boys can do a work in 29 days, then 12 men and 8 boys will do the same work in?      Log On


   

Question 698075: If 4 men or 7 boys can do a work in 29 days, then 12 men and 8 boys will do the same work in?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
If 4 men or 7 boys can do a work in 29 days, :
:
the job can be completed in
4*29 = 116 man-days
or
7*29 = 203 boy-days
:
:
"then 12 men and 8 boys will do the same work in?
:
let d = no. of days to do this
Let the completed job = 1,
:
Each will do a fraction of the job, the two fractions add up to 1
%2812d%29%2F116 + %288d%29%2F203 = 1
multiply equation by 23548 (203*116), results:
203(12d) + 116(8d) = 23548
:
2436d + 928d = 23548
:
3364d = 23548
d = 23548%2F3364
d = 7 days
:
:
Check this
%2812%2A7%29%2F116 + %288%2A7%29%2F203 =
%2884%29%2F116 + %2856%29%2F203 =
.724 + .276 = 1