Stats help...need to find the test statistic?

In a random sample of 500 urban drivers who own a cell phone, 270 admitted to using a cell phone while driving. In a random sample of 500 rural drivers who own a cell phone, 245 admitted to using a cell phone while driving. We are interested in the difference in population proportions of urban drivers compared to rural drivers (urban – rural). We are interested in performing a two-sided test for the null hypothesis that the population proportions of urban and rural drivers who admit to using a cell phone while driving are equal.