Answer:
z = 17.5
Step-by-step explanation:
segment RX is an angle bisector and divides the opposite side into segments that are proportional to the other 2 sides, that is
[tex]\frac{RS}{RT}[/tex] = [tex]\frac{SX}{TX}[/tex] , substitute values
[tex]\frac{15}{z}[/tex] = [tex]\frac{6}{7}[/tex] ( cross- multiply )
6z = 105 ( divide both sides by 6 )
z = 17.5
