Answer:
27 km/h
Explanation:
Let's take the direction in which Diego is travelling as positive direction. Therefore:
- Diego is travelling at a velocity of +7 km/h, towards the net
- The ball travels at +20 km/h towards the net, with respect to Diego's reference system
Therefore, the velocity of the ball with respect to the net reference system is equal to the sum of the two velocities:
[tex]v'=7 km/h+20 km/h=+27 km/h[/tex]
