Answer
$x\approx9.0952$
Work Step by Step
Transpose -4 to the other side.
$3(1.4)^x=64$
Divide both sides by 3.
$(1.4)^x=\frac{64}{3}$
Take the logarithm of both sides
$x\log1.4=\log(\frac{64}{3})$
$x=\frac{\log(64/3)}{\log1.4}\approx9.0952$
