What two quantities do you need to know to measure speed?

The distance traveled and the time it took to travel that distance.

Explanation:

You take the distance traveled (for example 3 meters), and divide it by the time (three seconds) to get the speed (one meter per second). Calculating the speed of an object, therefore, requires you to measure a distance and the time it takes to travel that distance.

complete the square on the right side of the equation;

-5(x + 0)^2 + 15

answer: d. y = -x^2 + 15