2-2=0
Lol, thanks! I appreciate it.
Hi!
We can set up a proportion to solve this

Cross multiply
3 x 16 = 48
48/12 = 4
The answer is 4
Hope this helps! :)
Now the first mechanic takes 4 days to do the job, so after he has worked for 1 day only, he has done 1/4 of the whole thing.
the second mechanic can do it in 6 days, so after 1 day only of work, he has done 1/6 of the whole thing.
the third mechanic can do it in 8 days, so after a day, he has done 1/8 of the total work.
now, if they all three work together, after 1 hour has gone by, the first mechanic has done 1/4 of the whole thing, the second mechanic has done 1/6 of it, and the last one, has done 1/8.
let's say it took all three working together "t" days, that means after 1 hour of work, they all combined have done 1/t of the whole thing, thus
(6 - 8x) + (-6 + 9x) = (6 - 8x) + (9x + (-6)) = (6 - 8x) + (9x - 6)
Commutative property: a + b = b + a