Answer:
Choice A, x=1
Explanation:
So, to start, there's two routes that you can take there. I am going to show one of these routes.
Within the image, you see two triangles, you are able to tell that these triangles share two of the same sides, because of congruency lines on each of them.
The first group of congruent sides have 1 line going through them, the second group has 2 lines going through them. Let's go with the first group.
With the first group, we are using the lines CB and FE, where the measurements on each of them are 3x+1 and x+3 respectively.
Since they are congruent, they are equal and we can just set them equal to each other.
Starting With:
3x+1 = x+3
Step 1) Cancel out the +1
3x+1 -1 = x+3 -1
3x = x+2
Step 2) Cancel out the x
3x -x = x+2 -x
2x = 2
Step 3) Divide by 2 get x by itself
2x/2 = 2/2
x=1
All done!