Alab technician mixed a 550 ml solution of water and alcohol. if 3% of the solution is alcohol, how many milliliters of alcohol were used, and how many milliliters of water were used?

The solution 550 ml total and first we will find the amount of alcohol. 3% = 0.03 550 ml x .03 = 16.5 ml alcohol
 Then to find the amount of water used, we just have to subtract the amount of alcohol from the total volume  
550 ml total - 16.5 ml alcohol = 533.5 ml water

What? i don’t understand

Decomposition is the cycle at which bacteria breaks down any organic material into the soil