Question 856032
arithmetic 
x-1,2x+5,8x-1
(2x+5)-(x-1)=(8x-1)-(2x+5)
x = 12/5
x-1 = 7/5, 2x+5 = 49/5, 8x-1 = 91/5
d=42/5

geometric
(2x+5)/(x-1)=(8x-1)/(2x+5)
(2x+5)/(x-1)=a,b=(8x-1)/(2x+5)
a = -2,   b = -2,   x = -3/4

ratio is -2 when x=-3/4

a = 3,   b = 3,   x = 8
ratio is 3 when x=8