# Math Help - Simple transposition ??

1. ## Simple transposition ??

Hi I have the following formula

A = (B+C)/C

A = 3
B = 10
C = ?

i know that C = 5 but how do I transpose to find C?

Thanks

Geoff

2. Hi

$A = \frac{B+C}{C}$

Multiplying by C

$AC = B+C$

$(A-1)C = B$

$C = \frac{B}{A-1}$

$C = \frac{10}{3-1} = 5$

3. Thanks

I understand upto

AC=B+C

Where does the -1 come from?

Geoff

4. $AC = B+C$

$AC - C= B$

Factorizing by C

$AC - C = (A-1)C = B$

$C = \frac{B}{A-1}$

$C = \frac{10}{3-1} = 5$