A graph of $f(x) = {-3x+9}$ is shown above. Using the geometry of the graph, evaluate the definite integrals.

1. $\displaystyle{ \int_0^1 \left({-3x+9}\right) \, dx }$ =
2. $\displaystyle{ \int_0^{{3}} \left({-3x+9}\right) \, dx }$ =
3. $\displaystyle{ \int_0^{{4}} \left({-3x+9}\right) \, dx }$ =
4. $\displaystyle{ \int_1^{{6}} \left({-3x+9}\right) \, dx }$ =
5. $\displaystyle{ \int_0^1 \left({-6x+18}\right) \, dx }$ =