How can I calculate revenue from cost and profit margin? Let's say I have a profit margin of 70% and expenses of $250 can I not calculate my estimated revenue? I'm using this formula: `Profit Margin = (Revenue - Expenses) / Revenue`. I'm trying to understand what my projected revenue would be given my profit margin and estimated cost. I'm looking for an answer in the form of a formula for Revenue like `R = ?`. This is probably elementary but any help is much appreciated. Thanks!

$$\text{Profit Margin} = (\text{Revenue} - \text{Expenses}) / \text{ Revenue}.$$

We'll use $P$ for profit margin; $R$ for revenue; and $E$ for expenses.

$$\begin{align} P = \frac{R-E}R &\iff RP = R-E \text{ (provided } R \
eq 0)\\\ \\\ &\iff RP - R = -E \\\ \\\ &\iff R(P - 1) = -E\\\ \\\ &\iff R = \frac E{1-P}\;\text{ (provided } P-1 \
eq 0) \end{align}$$

Now just "plug in" your values: $P = 0.7$, $E = 250$, to obtain revenue.