Answer: average speed is 8 km/h
Step-by-step explanation: in upstream his speed is 9 km/h -3km/h.
So his speed is 6km/h and he needs time t= s/v= 1.5 km: 6 km/h = 0.25 h
Downstream his speed is 9 km/ + 3km/h = 12km/h and time is
1.5 km:12km/h= 1/8 hours= 0.125 h
Average speed v = s/t = 3km: (0.25 + 0.125 ) h = 8 km/h
You use the for a cos(bx - c) + d to find your answer.
Amplitude = 5
Period = 2pi / 3
Phase shift = pi / 3 (moving to the right)
Midline or Vertical shift = 2
:)))