SOLUTION: A father and son are digging a garden that is 7 feet long and 5 feet wide. The father, working alone, can dig the garden in 3 hours. The son can do the job in 4 hours. If they both

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: A father and son are digging a garden that is 7 feet long and 5 feet wide. The father, working alone, can dig the garden in 3 hours. The son can do the job in 4 hours. If they both      Log On


   

Question 368453: A father and son are digging a garden that is 7 feet long and 5 feet wide. The father, working alone, can dig the garden in 3 hours. The son can do the job in 4 hours. If they both work together, how long would the two need to complete the task?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Rate*Time=Output
.
.
.
Let the output required to dig the garden equal Z.
R%2At=Z
Calculate the father's rate,
R%5Bf%5D%2A3=Z
R%5Bf%5D=Z%2F3
Calculate the son's rate,
R%5Bs%5D%2A4=Z
R%5Bs%5D=Z%2F4
Putting their rates together, calculate the time,
%28R%5Bf%5D%2BR%5Bs%5D%29%2At=Z
%28Z%2F3%2BZ%2F4%29%2At=Z
%284%2F12%2B3%2F12%29%2At=1
highlight%28t=12%2F7%29 hours