Question 149525
Let x=rate (projects per hour) at which Arvin works
Then 2x=rate at which Gian works (works twice as fast)
Together they work at the rate of x+2x=3x projects per hour

But we are told that together, they work at the rate of 1/(4 2/3) projects per hour= 3/14 projects per hour.  So our equation to solve is:
3x=3/14  divide each side by 3
x=1/14 project per hour----------------rate at which Arvin works
Now if z=amount of time it takes Arvin to do the project, then
(1/14)*z=1 (1 project, that is)
z=14 hours---------------amount of time it takes Arvin working alone
Also:
2x=2(1/14)=2/14 projects per hour-------------------rate at which Gian works

CK
1/14 + 2/14=1/(4 2/3)=1/(14/3)=3/14
3/14=3/14

Hope this helps---ptaylor