Question 146772
First painter's rate: 1 house per 12 hours or 1/12
Second painter's rate: 1 house per 8 hours or 1/8
.
Let x = combined time it would take BOTH to paint a single house
then
(1/12)x + (1/8)x = 1
multiplying both sides by a "common denominator" (96) we get:
96[(1/12)x + (1/8)x] = 96*1
8x + 12x = 96
20x = 96
x = 96/20
x = 4.8 hours
.
or (since there are 60 minutes per hour)
x = 4 hrs (.8*60) mins
x = 4 hrs 48 mins