## Calculus (3rd Edition)

$$f(t)=10e^{-0.7t}.$$
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 $$f(t)=10e^{-0.7t}.$$