# Message from ThisIsChris in MacGuyver - Skills &amp; Academics#homework-help

so on the left you have 45 u

an the right the 5 on the bottom cancels out with the 5 on the top you just multiplied

so 45u = 6

then divide both sides by 45

so u = 6/45

6 is 2\*3, and 45 = 15\*3

so u = (2\*3)/(15\*3)

the 3 on top and bottom cross out

so u = 2/15

@Warren H oh you want it the way they did it in the picture? it is similar:

starting from 9u = 6/5

Your way seems easier. There's was confusing as heck

How did you know 15 x 3? Instead of 9x5?

I'll do it closer to the way they did it:
starting from 9u = 6/5
divide both sides by 9, so u = (6/5) * (1/9)

so u = 6/(5*9)

now 6 is 2\*3 and 9 is 3\*3

so u = (2\*3)/(5\*3\*3)

cross out a 3 on top and bottom

Ohh okay.

so u = 2/(5*3)

so u = 2/15

yep

So I do that every time? Divide both sides by whatever the number is?

Yep that will always work

Awesome thanks. One more, this one is a negative number. I'm guessing it works the same?

-4w = 6/7

So divide both sides by -4 and I get 6/7 * 1/4? Or -1/4

Yep:
divide both sides by -4, so w = 6/(7* -4)
6 is 2\*3 and -4 is 2\*-2
so w = (2\*3) / (7\*2\*-2)
then cross out the two on top and bottom
so w = 3/(7*-2)
so w = 3/(-14) or equivalently w = -3/14

@Warren H the second one

the negative sign stays with the number it is attached to

Okay. So I got 3/7 the first time. But it's actually negative 3/14ths? Or -3 over 14?

Yep. If you're asking if there is a difference between " negative 3/14ths vs -3 over 14" the answer is no, they have the same value

Uh. Divide both sides by 9

Oh geez

I didn't see all this

@Warren H One thing you might notice at the beginning: think about the equation -4w = 6/7

one things you might notice is that the left side is -4 * w, and the left side is a positive number (specifically 6/7)

that means w times a negative number is something positive

so whatever w is, w must be some negative number, since -4 times a positive number would be negative.

@Warren H This ^ might help as a kind of double check on your work, thinking what sign the final answer should have