Answer:
We have to add 14 mL of water to dilute the alcohol solution from 13% to 6% 
Step-by-step explanation:
Step 1: Data given
Original solution has 12 mL of 13% alcohol
New volume has a concentration of 6%
Step 2: Determine how much pure alcohol you have in the solution. 
 0.13 * 12ml = 1.56 ml pure alcohol. 
 
Step 3: Calculate ratio alcohol: total in volume
 1.56 ml / 12 ml = .013
 
Step 4: add water to the total solution and set the desired percentage
 
1.56 ml / (12ml + x) = 0.06 
 1.56 = 0.06 (12 + x) 
 1.56 = 0.72 + 0.06x 
 0.84 = 0.06x
x = 14
We have to add 14 mL of water to dilute the alcohol solution from 13% to 6%