The ROI (Return on Investment) is a typical business metric for profitability and efficiency of your marketing investments. The ROI metric is calculated using this simple formula and is returning a %:
If negative, this means that the invest has not achieved any returns and you should consider looking carefully into it, or even stop it entirely. But also consider into your strategic decisions that ~60% of the effect of adverting is only be measured in the long term. You probably only have a fraction of your actual revenue generated from the investment in your books right now.
Your ROI: %
Another way to inspect the efficiency of a marketing or advertising investment is the ROAS which compares the advertising budget spent vs. the gained sales.