Person A can paint the house 2 times as fast as person B. This year person A and B worked together, it took them 3 days. How long would it take each to paint the house

Question

Person A can paint the house 2 times as fast as person B.  This year person A and B worked together, it took them 3 days.  How long would it take each to paint the house

phi · Answer

I like to think of these problems as close to "rate * time = distance"
except instead of distance, it is "work"

Let's say B paints x houses per day  (his rate is x houses/day)
the A paints twice as fast, or 2x
together we have
(2x+1x) houses/day * 3 days = 1 house
solve for x