A bakery made 100 donuts in the display case 40/100 were chocolate 3/10 were glazed and the rest were cinnamon which fraction of the donuts were cinnamon? 30/100 , 43/100 , 57/100, 70/100

Cinnamon donuts were equal to:

100 - (40 + 10)
100 - 50
= 50

So, the fraction of the donuts that were cinnamon is:
50/100
= 1/2

Therefore, 1/2 or 50/100 of the donuts were cinnamon.