Question 906514
You asked another one like this in which only two of the values were different but the description and question were the same.


1 job is "paint the fence"


RATES in jobs per hours
Ralph, {{{1/m}}}
Lisa, {{{1/f}}}


Both questions used 45 minutes for the time that Ralph  (m for male) painted alone; which is
{{{3/4}}} hour.  Let x be the time that Ralph and Lisa  (f for female) work together after
Ralph worked alone.


{{{highlight_green((1/m)(3/4)+(1/m+1/f)x=1)}}}, accounting for ONE WHOLE JOB.
One equation, three variables, but m and f are to be used as known constants, and only
x is the unknown variable to be solved.  Solve for x.