# 4 variable equation

1. Aug 9, 2012

### Biaqua

For my work, I need to solve the following equation for the variable x (if possible):

a * (x/1000) = b - x * c

Can someone please help me solve it or inform me that it is simply not possible. I'm chemist myself, so solving equations is not exactly my expertise.

2. Aug 9, 2012

### micromass

Staff Emeritus
First, add up c*x to both sides of the equation. Then isolate x from the left side.

Last edited: Aug 9, 2012
3. Aug 10, 2012

### Biaqua

Thanks, but I already got to that point. The thing is that I don't know how to solve the (x/1000) part.

4. Aug 10, 2012

### acabus

Multiply both sides by 1000.

5. Aug 10, 2012

### dydxforsn

Just to make it abundantly clear:

$$\frac{a}{1000} x = b - c x$$
$$\frac{a}{1000} x + c x = b$$
$$(\frac{a}{1000} + c) x = b$$
$$x = \frac{b}{\frac{a}{1000} + c}$$
$$x = \frac{1000 b}{a + 1000 c}$$