Question

Simon is riding a bike at 12 km/h away from his friend Keesha. He throws a ball at 5 km/h back to Keesha, who is standing still on a sidewalk. How fast would Keesha say the ball is traveling?

Answer 1

the answer is B

Step-by-step explanation:

Answer 2

So there are different ways this could be solved. I'll do try to explain it the way I was taught...

Simon is riding his bike at 12 km/hr relative to the sidewalk, away from where Keesha is.

Simon throws the ball at Keesha, at 5 km/hr.

Keesha sees the ball approaching her at (12-5) = 7 km/hr relative to the ground to her.

Therefore the answer is: 7 km/hr