Answer:
1:4
Explanation:
Ratios and Fractions
It's given 1/5 of the chocolates in a box contain nuts. The rest do not contain nuts. The portion that does not contain nuts is:

We need to calculate the ratio of the number of chocolates that contain nuts to the number of chocolates that do not contain nuts.
This can be done by dividing 1/5 by 4/5:

Operating:

Expressing it as a ratio: 1:4