29.15 is a mixed number in simplest form is 293/20
Look at attached photo
first divide each line into the number as shown in the denominator
If I've read this correctly, it looks like this.

If that is correct, then the first step is to put the top part of the denominator over 3x
The next part is to flip a three tier fraction. I'm afraid I have to show what happens. My latex is not that strong.
What you get is

This is just about your final answer. You could write it as

Answer:
Distance of the point from its image = 8.56 units
Step-by-step explanation:
Given,
Co-ordinates of point is (-2, 3,-4)
Let's say



Distance is measure across the line

So, we can write




Since, the equation of plane is given by
x+y+z=3
The point which intersect the point will satisfy the equation of plane.
So, we can write




So,









Now, the distance of point from the plane is given by,






So, the distance of the point from its image can be given by,
D = 2d = 2 x 4.28
= 8.56 unit
So, the distance of a point from it's image is 8.56 units.
What is your question I will answer it if I can