Answer:
They traveling at
in backward direction.
Step-by-step explanation:
Given mass of Ammy 
and velocity is forward at 
Also, mass of Jenny 
Who is travelling in opposite direction 
Let velocity in forward direction is positive and velocity in backward direction is negative.
Also, velocity after crash is 
As they crashed into each other and they moved as one mass. We can apply principle of conservation of momentum.
Conservation of momentum says momentum before collision should equal to momentum after collision.


So, velocity after collision
≅
is in opposite direction. That is the direction of Jenny.
480=60(v+s)
480=60v+60s
8=v+s
s=8-v...
480=80(v-s) using s from above we get:
480=80(v-(8-v))
6=v-8+v
6=2v-8
2v=14
v=7, and since s=8-v, s=1
So the rate of the team is 7m/s while the rate of the stream is 1m/s
The answer is x=3 i believe
2.25h(60m/hr)(1/3)=45m
So Rick spends 45 minutes studying math per night.
The correct answer would be B! :)