2
C(v) = 0.045 v  - 6.75 v + 393

Next question: what is the speed v when the emission C(v) amounts to 200 g/km?

You can read an approximate solution directly from the graph. If you know how to solve quadratic equations, you can compute the answer directly, using the equation.

There are two solutions. Enter your first solution here (rounded to km/h):

Enter your second solution here (rounded to km/h):