Can someone please help?

Answer:
Well a midpoint makes the cutter segment or Line in exactly in half. So the two lines cutted are equal. In this case t is the midpoint. PT and TQ are equal. So you have two expressions, make then equal to each other since they are congruent.
6x+4=8x-8
12=2x
x=6
Now PT is 6x+4
So we subsitute x for 6 since x=6
6*6+4
40
PT is 40