What answer describes this sequence?
99, 89.9, 78.8, 68.

a) neither arithmetic nor geometric
b) both arithmetic and geometric
c) arithmetic
d) geometric

A) Neither arithmetic nor Geometric

Explanation:
Since 99-89.9= 9.1, and 89.9 - 78.8 = 11.1, the sequence is not arithmetic.
Like wise 89.9/99=0.908 and  78.8/89.9 = 0.876 makes it not a geomtric sequence