
Mark M. answered 04/26/19
Mathematics Teacher - NCLB Highly Qualified
Assumption must be made that all men are equally efficient and all women are equally efficient.
m represents the work of 1 man
w represents the work of 1 woman
J represents the entire job
4m + 3w = J/6 one days work
5m + 7w = J/4 one days work
8m + 6w = 2J/6 multiply top equation by 2
13m + 13w = 2J/6 + P/4 add two equation
13m + 13w = 4J/12 + 3P/12
13m + 13w = 7J/12
m + w = 7J/(12*13)
m + w = 7J/156
The two take 156/7 or 22 and 2/7 days