# Math Help - formula rearrangement

1. ## formula rearrangement

Hi,

having trouble with arranging formulae that have a negative sign. i.e.

a - bx = m
- bx = m - a
x = [m - a][/-b]

thats my working of the problem

but the text book answer is: x = [a - m][/b]

what am I doing wrong?

2. Originally Posted by nativecat
Hi,

having trouble with arranging formulae that have a negative sign. i.e.

a - bx = m
- bx = m - a
x = [m - a][/-b]

thats my working of the problem

but the text book answer is: x = [a - m][/b]

what am I doing wrong?
You haven't done anything wrong.

Remember that $p - q = -(q - p)$ and that a negative times/divided by a negative gives a positive.

So from your working you've ended up with

$x = \frac{m - a}{-b}$

$= \frac{-(a - m)}{-b}$

$= \frac{a - m}{b}$.