<span>93000000
...........................................</span>
Since z is the midpoint, rz and zt must be equal
4x - 15 = 25
4x = 40
X = 10
Plug the answer in and rz equals 40-15 which is 25.
25 + 25 = 50
Or if you really wanted, since you know 25 is half, just add them together right off the bat. (25 and 25, I mean)
