Question 998050
Qualified painter, one-man rate,  {{{1/x}}}
Apprentice, one-man rate,  {{{1/(x+15)}}}


The next or second sentence uses the idea that if n agents are acting, and r is the rate of one agent, then the rate of n agents acting is  n*r.


The 3 apprentices and two qualified painters:
This is the rate of the described group:   {{{3(1/(x+15))+2(1/x)}}}


That group does 1 job in the given  {{{25/8}}} days.
{{{(3/(x+15)+2/x)(25/8)=1}}};
Solve for x in the rational equation.; and then evaluate x+15.