Answer:
The length of MN is 30.
Explanation:
It is given that △XYZ maps to △MNO with the transformation

This rule of transformation represents the dilation with scale factor 5 because the dilation about the origin is defined as

where, k is scale factor.
In dilation, the image and preimage are similar and scale factor is the ratio of corresponding side of image and preimage.
In △XYZ and △MNO,


Multiply both sides by 6.

Therefore the length of MN is 30.