Question 130566
Let x=amount of time it take all three working together to do the job
Now we know that:
Tom works at the rate of 1/3 job per hour
Dick works at the rate of 1/4 job per hour
Harry works at the rate of 1/6 job per hour

Together they work at the rate of 1/3 +1/4 +1/6 job per hour or
8/24 + 6/24 +4/24=18/24=3/4 job per hr

Now our equation to solve is:

(3/4)*x=1 (1 job, that is)  multiply both sides by 4
3x=4
x=1 1/3 hours ---amount of time it takes all three working together

Hope this helps---ptaylor