Find Gross from Net and Percentage I would like know if a simple calculation exists that would allow me to determine how much money I need to gross to receive a certain net amount. For example, if my tax rate was 30%, and my goal was to take home 700, I would need to have a Gross salary of $1000. 

Let $x$ be the gross amount needed, and $y$ be the desired net amount, and $r$ be the rate of taxation.
Then,
$$x\times\left(1-\frac{r}{100}\right) = y\\\implies x=\frac{y}{1-\frac{r}{100}} = \frac{100y}{100-r}$$
