Answer
$$ f(t)=10e^{-0.7t}.$$
Work Step by Step
The solution of the differential equation is given by
$$ y=f(t)=Ce^{-0.7t}.$$
To find $ C $, we use the initial condition $ y(0)=10$; then we have $ C=10$.
Hence the solution is
$$ f(t)=10e^{-0.7t}.$$
