Answer
$80$
Work Step by Step
Using the formula: we know that $70=10\log{\frac{x}{10^{-12}}}$, thus $x=10^{-5}$ is the equation for the car. For the truck the intensity is $10x=10^{-4}$, hence
$L=10\log{\frac{10^{-4}}{10^{-12}}}=10\log{10^8}=10\cdot8=80$
