Question 1154714
h, time for Howard alone to do one job
18, time for Edward to do one job


First two sentences
{{{1/h+1/18=1/12}}}

{{{1/h=1/12-1/18}}}

{{{36/h=36(1/12-1/18)}}}

{{{36/h=3-2}}}

{{{36/h=1}}}

{{{highlight_green(h=36)}}}


Last three sentences
x, how many hours Edward worked alone to finish job
(No need to know h)
{{{(1/12)*4+(1/18)x=1}}}

{{{1/3+x/18=1}}}

{{{6+x=18}}}

{{{highlight(x=12)}}}