Answer
$1.50\times10^{24}$ molecules of ethanol
Work Step by Step
Multiply the volume of 145mL by the given density of ethanol (remember that $cm^{3}$ is the same as milliliters). Then multiply by the molar mass of ethanol which can be calculated by adding the molar mass of its constituent elements. Finally, multiply by Avogadro's number to get the number of molecules. Notice how all units but molecules cancel each other out.
$145 mL \times \frac{0.789g}{1mL}\times\frac{1 mol}{46.068g}\times\frac{6.022\times10^{23}molecules}{1 mol} = 1.50\times10^{24} molecules$