e stand for euler's konstant=2.718281828...
14*e^t = 9*(4.8)^t
e^t=(9/14)*4.8^t...0.642857142*(4.8)^t
ln(e^t)=t.....=ln(0.642857142) + t*ln(4.8)]
t*[1-ln(4.8)]=ln(0.642857142)=-0.441832752
t=-0.441832752 / [1-1.568615918]
=-0.441832752 / (-0.568615918)
=+0.777031979