U=F(r+B) I can't figure out what r equals

Anonymous, if you join up, which is extremely easy, then you will be able to edit your posts. 

Lets look at this

$$$U=F(r+B)$ First you need to get rid of the F. So you divide BOTH sides by F\\\\
$\frac{U}{F}=\frac{F(r+B)}{F}$\\\\
$\frac{U}{F}=r+B$\\\\
Now you need to get rid of the B off the RHS so you subtract it from both sides\\
$\frac{U}{F}-B=r+B-B$\\\\
$\frac{U}{F}-B=r$\\\\
$r=\frac{U}{F}-B$\\\\$$

r= b$${\mathtt{r}} = {\frac{{\mathtt{U}}}{{\mathtt{f}}}}{\mathtt{\,-\,}}{\mathtt{b}}$$  Hope this helps :)

FORM ABOVE, IGNORE THE OTHER r=b, it wont let me edit it out, sorry