Answer
750 mL of champagne has 83 mL of alcohol
Work Step by Step
$11\%$ (v/v) $ alcohol $ solution : $$ 11 \space mL \space alcohol = 100 \space mL \space solution$$
$$750 \space mL \space solution \times \frac{11 \space mL \space alcohol}{100 \space mL \space solution} = 83 \space mL \space alcohol $$