Answer: There are 350 milliliters of alcohol in the bottle 
Explanation:
 Step 1
 The amount of solution contained in the bottle = 500 millilitres
 The percentage of alcohol contained in the bottle of 500 millilitres= 70%. 
 
Therefore amount of alcohol in the solution is 70% of 500 millilitres
 
 Step 2 --- Solving we have 
70/100 × 500 = 0.70 x 500 = 350 ml 
 
 There are 350 millilitres of alcohol in the bottle.