When the same constant is added to the numbers 60, 120, and 140, a three-term geometric sequence arises. What is the common ratio of the resulting sequence?
(120 + x) / (60 + x) = (140 + x) / (120 + x)
(120 + x) (120 + x) = (60 + x) (140 + x)
14400 + 240x + x^2 = 8400 + 200x + x^2
14400 - 8400 = 200x - 240x
6000 = - 40x
-6000/40 = x = -150
The ratio is [ 120 - 150 ] / [ 60 -150 ] = [ -30] / -90 ] = 1 / 3
+656 
