UK Whitgift School Entrance Exam Groups B and C Question \#$9$)  A box of kiddimix contains $20$ chocolates of which $8$ are plain chocolates and $12$ are milk chocolates. If $16$ of the $20$ have soft-centres, what can you say about how many plain chocolates there are with soft-centres? 
Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Fractions and Percentages->Knowing the Base