Question 774362
t takes 1 person 2 hours to paint a car.
 It takes another person 4 hours to paint a car.
 Another person also takes 4 hours to paint a car.
How long will it take all of them to paint 1 car.
:
Let t = time for all three to paint the car
Let the completed job = 1
:
Each will do a fraction of the job, the three factions add up to 1
{{{t/2}}} + {{{t/4}}} + {{{t/4}}} = 1 
multiply by 4 to clear the denominators, resulting in:
2t + t + t = 4
4t = 4
t = 1 hr for all three to do the job