Hey there!!
The line which is arising from the center point cuts the chord into exact halves.
Remember, the diameter always cuts the chords into equal halves.
Hence, this would result as:
... 5x-7=3x+5
Subtracting 3x on both sides:
... 2x-7=5
Adding 7 on both sides:
...2x=12
Dividing by 2 on both sides:
... x=12/2
... x=6
<em>Hence, the value of 'x' is 6. </em>
<em>Hope this helps!</em>