Koko can paint a room two hours less than Andre.
Suppose Andre cn paint a room in x hours.
Then Koko can pain a room in x-2 hours
So Andre's painting rate is 1 room per x hours or or
And Koko's painting rate is 1 room per x-2 hours or or
If they will work together, they can finish the job in 12 hours.
So their combined painting rate is 1 room per 12 hours or or
The equation comes from
Multiply through by LCD of 12x(x-2)
x^2-2x}}}
x^2-2x}}}
That doesn't factor, so
Solutions x=25.04159458 and 0.9584054212
The second answer makes no sense since (1) we can't subtract 2 from it and
get a positive answer, and (2) if Andre being able to finish in less than
an hour makes no sense. :)
Answer: It would take Andre a little over 25 hours and Koko a little
over 23 hours.
Edwin