The first and ninth terms of an arithmetic sequence are 2/3 and- 4/5, respectively. What is the fifth term?
The fifth erm is 3/8.
t1 = 2/3
t9 = t1 + 8d ---> -4/5 = 2/3 + 8d ---> -22/15 = 8d ---> d = -11/60
t5 = t1 + 4d ---> t5 = 2/3 + 4(-11/60) = -1/15
