9. You are pushing your friend in his wheelchair. You are both taking his dog, Wrathbone, to the vet. Wrathbone is 5 kg and is sitting in your friend's lap. You decide to increase the wheelchair's acceleration to 7 m/s^2 in order to get up a steep ramp. If your friend has a mass of 46 kg and his wheelchair has a mass of mass 16 kg. What is the force you are applying?