P = P0(1+r)t
Where P represents current principal, P0 represents original principal, r represents rate, and t represents time. Let's replace all the variables & try to find the rate of growth.
156,000 = 126,000(1+r)8
156000/126000 = (1+r)8
26/21 = (1+r)8
(26/21)1/8 = 1+r
r = (26/21)1/8 - 1 = 1.027 -1 = .027 = 2.7%