Answer:
d = -6
Step-by-step explanation:
t1 = 7, t2 = 1, t3 = -5, t4 = -11
t2 - t1 = 1 - 7 = -6
t3 - t2 = -5 - 1 = -6
t4 - t3 = - 11 - (- 5) = -11 + 5 = -6
Therefore, the common difference is constant( I. e -6). Therefore the common difference is -6.
