A pinata is filled with Sour Patch Kids, Starbursts, variety of chocolate bars, and Skittles. There is total of 50 pieces of large sized candy. 12 are Sour Patch Kids, 5 are Starbursts, and 13 are a variety of chocolate bars.
Fill in the blank in the sentence below.
The ratio of chocolate bars to the total amount of non chocolate bars ( all the other candy) is __:__
