Answer:
9
Step-by-step explanation:
If S is between R and T, then RS+ST = RT
Given the following parameters
RS=2z+6,
ST=4z−3,
RT=5z+12
On substituting
2z+6+4z-3 = 5z+12
Collect like terms
2z+4z-5z = 12+3-6
6z-5z = 15-6
z = 9
Hence the value of z is 9
