Question 979975
RT=J uniform rate model relating RATE, TIME, Amount of JOB.


The two farmers are farmer A at rate A and farmer B at rate B.
The rate model form can also be shown as {{{R=J/T}}}, and we can then use
this to assign {{{A=8/6=4/3}}}  and {{{B=6/9=2/3}}}, both in units of TREES per DAY.


Their combined rate if working together on the same work is  {{{A+B}}}.


Question, how many trees j can A and B plant in t=15 days?  The unknown variable is j.
{{{(A+B)*t=j}}}


{{{highlight_green(j=(4/3+2/3)*15)}}}
and you can do the arithmetic computation.