if h(t) = 17.4 * 1.23^t, find t when z(t) = 144

I assume h(t) and z(t) are the same.

144 = 17.4 * 1.23^t
144/17.4 = 1.23^t
log(144/17.4) = t*log 1.23
t = log8.276/log1.23

whatever that comes out to . . .