If a media plan targets the 50 million Gen Xers currently living in the U . S , then a reach of 20 means that

If a media plan targets the $\mathrm{50}$ million Gen Xers currently living in the U$.$S$,$ then a reach of $\mathrm{20}$ means that $\_\_\_\_$ million members of the target audience will be exposed to at least one of the media vehicles in the plan.