An advertising ﬁrm has an old computer that can prepare a whole mailing in 6 hours.
With the help of a newer model the job is complete in 2 hours. How long would it
take the newer model to do the job alone?

Question

An advertising ﬁrm has an old computer that can prepare a whole mailing in 6 hours.
With the help of a newer model the job is complete in 2 hours. How long would it
take the newer model to do the job alone?

anonymous · Answer

I got 1/6 +1/x = 1/2 then 1/x = 1/2 -1/6 = 1/3

anonymous · Answer

I got 1/x = 1/3 what's next?

ganeshie8 · Answer

your goal is to solve $x$

anonymous · Answer

Yeap I know but how would I translate 1/x to x=3 I know 3 is the answer but how will I get there

ganeshie8 · Answer

1/x = 1/3

flip both sides and get
x/1 = 3/1

which is same as
x = 3

anonymous · Answer

You just flip it? No math explanation?

ganeshie8 · Answer

flipping is mathematical.
for nonzero real numbers, we have :
$$\dfrac{a}{b} = \dfrac{c}{d} \implies \dfrac{b}{a}=\dfrac{d}{c}$$

anonymous · Answer

Oh I thought when you flip it becomes
$$x^-1 = 3$$

anonymous · Answer

wait a minute I could've use cross multiply!!!

ganeshie8 · Answer

Yes you could do that too

anonymous · Answer

Yeah thank you for lending me a hand. I'm doing crash course for my engineering math exit. Thank you!

ganeshie8 · Answer

np, good luck with the course!